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CCNA 200-301 v2 (200-301) — Questions 12011275

1389 questions total · 19pages · All types, answers revealed

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1201
Multi-Selectmedium

Which two statements accurately describe good management-plane security practice on network devices?

Select 2 answers
A.Use secure management protocols such as SSH instead of less secure remote-access methods.
B.Restrict management access to trusted source networks where possible.
C.Prefer shared generic admin accounts for convenience.
D.Disable all logging to reduce device workload.
E.Rely only on SSID names to protect router management.
AnswersA, B

Secure management protocols like SSH provide encrypted transport and strong authentication for administrative sessions, preventing credential theft and session hijacking over the network. In contrast, protocols such as Telnet or HTTP transmit passwords and configuration data in plaintext, which attackers can easily intercept. Protecting the management plane with encryption is a foundational best practice for network device security.

Why this answer

Good management-plane security combines multiple layers of control. In practical terms, using secure protocols such as SSH is important, but so is restricting which sources may connect, controlling who is authorized, and maintaining visibility into administrative activity. Strong management security is not usually one setting by itself.

This is a layered-control question rather than a single-technology question.

Exam trap

A common exam trap is selecting only one security measure, such as using SSH, and ignoring the importance of restricting management access sources. Candidates might assume that encrypted protocols alone provide complete security, but without source filtering, attackers can still attempt unauthorized connections. Another trap is choosing options that suggest disabling logging or using shared admin accounts, which weaken security by reducing accountability and visibility.

The exam tests understanding that management-plane security is multi-layered, requiring both secure protocols and access restrictions to effectively protect network devices.

Why the other options are wrong

C

Incorrect because shared generic admin accounts reduce traceability and accountability, making it difficult to audit who made changes or accessed the device, which weakens security.

D

Incorrect because disabling logging removes visibility into management activities, hindering the ability to detect unauthorized access or troubleshoot issues, which is counterproductive to security.

E

Incorrect because SSID names pertain to wireless network identification and do not provide any protection for router management-plane access or protocols.

When would these options actually be correct?

C

If an exam question asked about user management practices in a small, isolated environment where convenience is prioritized over security, and where user accountability is not a concern, then preferring shared generic admin accounts could be considered acceptable.

D

In a question focused on optimizing performance for low-resource devices in a controlled environment, where logging is deemed unnecessary due to limited access and oversight, disabling logging could be considered acceptable.

E

In a question focused on basic home network security practices where the context is about minimizing complexity for non-technical users, an option suggesting that SSID names can serve as a layer of obscurity might be considered acceptable.

Why candidates pick the wrong answer

C

Candidates may choose this option due to a misunderstanding of the balance between convenience and security, believing that shared accounts simplify management without recognizing the security risks involved.

D

Candidates may choose this option believing that reducing logging will enhance device performance and reduce resource consumption, especially if they have encountered scenarios where excessive logging was an issue.

E

Candidates may mistakenly believe that SSID names provide a level of security by obscurity, especially if they lack understanding of more robust security measures like encryption and proper access controls.

1202
MCQmedium

A switch shows this output from the "show interfaces trunk" command: Gi0/1 on 802.1q trunking 1 Gi0/2 auto 802.1q not-trunking 1 Which statement is correct?

A.Gi0/1 is an access port in VLAN 1
B.Gi0/1 is trunking, and Gi0/2 is waiting for DTP negotiation
C.Gi0/2 is forced to trunk mode
D.Neither interface can carry tagged traffic
AnswerB

The output shows Gi0/1 with DTP mode 'on' and the operational state 'trunking' with 802.1Q encapsulation, meaning it is actively carrying tagged frames for multiple VLANs. Gi0/2 is in 'auto' mode, a passive DTP setting that neither initiates nor advertises trunking but listens for DTP frames from its neighbor. If the neighbor is set to 'on' or 'desirable', Gi0/2 will successfully negotiate and become a trunk as well; until then, it remains in a waiting/negotiation state.

Why this answer

Gi0/1 is already operating as an 802.1Q trunk. Gi0/2 is in dynamic auto mode, which waits for the other side to actively negotiate trunking.

Exam trap

Beware of confusing 'on' with access mode and misunderstanding dynamic auto's capability to negotiate trunking.

Why the other options are wrong

A

This option is incorrect because Gi0/1 is configured as a trunk port, not an access port, and it is actively trunking VLANs. Access ports do not participate in VLAN tagging and would not show trunking status.

C

This option is incorrect because Gi0/2 is set to 'auto' for trunking, meaning it is not forced into trunk mode but is instead waiting for Dynamic Trunking Protocol (DTP) negotiation to determine if it should become a trunk port.

D

This option is incorrect because Gi0/1 is configured as a trunk port and can carry tagged traffic, while Gi0/2 is in a state waiting for DTP negotiation, which means it can potentially become a trunk port as well.

When would these options actually be correct?

A

In a different scenario where the question specifies that Gi0/1 is configured as an access port and VLAN 1 is the only VLAN present, this option would be correct. The question could state that the switch is set to default configurations without any trunking enabled.

C

In a different scenario where the question specifies that Gi0/2 is explicitly configured with the 'switchport mode trunk' command, this option would be correct as it would indicate that Gi0/2 is indeed forced into trunk mode regardless of DTP negotiation.

D

If the question were to state that both interfaces are configured as access ports and there is no mention of trunking or DTP negotiation, then option D would be correct, as neither interface would be able to carry tagged traffic in that scenario.

Why candidates pick the wrong answer

A

Candidates may choose this option due to a misunderstanding of port roles; they might confuse trunk ports with access ports, especially if they recall that VLAN 1 is often the default VLAN for access ports.

C

Candidates may find this option tempting because they might misinterpret the 'auto' setting as an indication that the port is actively configured to trunk, leading them to assume it is forced into that mode.

D

Candidates may choose this option due to a misunderstanding of trunking and access port configurations, leading them to incorrectly assume that if an interface is not explicitly set to trunk, it cannot carry tagged traffic.

1203
Multi-Selectmedium

A branch router is running single-area OSPF. An engineer wants an interface to advertise its connected network into OSPF but must prevent hello packets from being sent on that LAN segment. Which two actions achieve that goal?

Select 2 answers
A.Enable OSPF on the interface or matching network statement
B.Configure the interface as passive in the OSPF process
C.Set the interface network type to point-to-point
D.Apply distribute-list out on the interface
AnswersA, B

Enabling OSPF on an interface directly using `ip ospf <process-id> area <area-id>` or via a `network` statement under the OSPF process configuration ensures the connected network is advertised into the OSPF routing domain. This action directly satisfies the requirement to advertise the interface's connected network into OSPF, forming one part of the overall solution.

Why this answer

In OSPF, a passive interface still advertises the connected network but does not send or process hello packets. So the interface must participate in OSPF, and then it must be made passive.

Exam trap

A frequent exam trap is assuming that changing the OSPF network type or applying a distribute-list on the interface will stop hello packets. Many candidates mistakenly believe that setting the interface to point-to-point suppresses hellos, but it only changes adjacency behavior. Similarly, distribute-lists filter routing updates but do not affect hello packet transmission.

The key mistake is forgetting that OSPF must be enabled on the interface to advertise the network and that only the passive-interface command prevents hello packets while still advertising the connected subnet.

Why the other options are wrong

C

Setting the interface network type to point-to-point changes adjacency behavior but does not suppress hello packets. Therefore, it does not meet the requirement to prevent hello packet transmission.

D

Applying a distribute-list out on the interface filters routing updates but does not affect the sending of OSPF hello packets. It does not prevent hello packet transmission on the LAN segment.

1204
Multi-Selecthard

Exhibit: A static route to 172.16.40.0/24 is configured, but traffic still follows the default route. Which two explanations are plausible?

Select 2 answers
A.The next hop for the static route may not be reachable
B.The exit interface associated with that path may be down
C.The default route always overrides more specific routes
D.Static routes require a metric lower than 1
E.The destination prefix must be configured under router ospf first
AnswersA, B

When a static route is configured with only a next-hop IP address, the router must perform a recursive route lookup to determine the exit interface and next-hop reachability. If that next-hop IP is not reachable—meaning there is no valid route in the routing table to that IP—the static route will not be installed in the routing table. This commonly happens when the next hop is on a directly connected network that is down or has no matching connected route.

Why this answer

If a static route points to an unreachable next hop or the outgoing interface is down, the route may not be installed as usable. In that case the router can still use a less specific route such as the default route.

Exam trap

A frequent exam trap is believing that a static route always takes precedence over a default route regardless of network conditions. Candidates may overlook that Cisco routers require the next hop to be reachable and the exit interface to be operational before installing the static route. If these conditions are not met, the router ignores the static route and uses the default route instead.

This misunderstanding can lead to incorrect answers, especially when the question involves static route reachability or interface status.

Why the other options are wrong

C

Incorrect because Cisco routers use the longest prefix match rule, meaning a more specific static route overrides the default route when valid. The default route does not always override specific routes.

D

Incorrect because static routes do not require a metric lower than 1. Static routes have an administrative distance of 1 by default, but metric values do not prevent route installation based on reachability.

E

Incorrect because static routes operate independently of dynamic routing protocols like OSPF. The destination prefix does not need to be configured under OSPF for a static route to function.

When would these options actually be correct?

C

In a scenario where policy-based routing (PBR) is configured to match the default route and forward traffic differently, or if the question specifies that the default route has a lower administrative distance than the static route (e.g., static route is learned via DHCP with AD 254, while default is OSPF with AD 110).

D

In a scenario where a routing protocol like OSPF is used and the question asks about the metric range for OSPF, the correct answer might be that OSPF uses a metric from 1 to 65535, but a metric of 0 is invalid.

E

In a question about OSPF route redistribution, where a static route must be redistributed into OSPF, the destination prefix must be configured under 'router ospf' with a 'redistribute static' command for OSPF to advertise it.

Why candidates pick the wrong answer

C

Candidates may confuse the concept of administrative distance with prefix length, mistakenly thinking a default route can override a more specific route if it has a lower AD, or they may misunderstand that static routes always take precedence over dynamic defaults.

D

Candidates may confuse metric with administrative distance or think that static routes need a low metric to be preferred over dynamic routes.

E

Candidates may confuse the configuration requirements of dynamic routing protocols like OSPF with the simpler configuration of static routes, assuming that all routes need protocol-specific setup.

1205
MCQhard

Which IPv6 prefix is used for link-local addresses?

A.FC00::/7
B.FE80::/10
C.2000::/3
D.FF00::/8
AnswerB

IPv6 link-local addresses are uniquely identified by the FE80::/10 prefix, which is reserved for communication solely within a single network segment. This specific prefix ensures that packets with these source or destination addresses never traverse a router, satisfying the constraint of being confined to the local link. Every IPv6-enabled interface automatically configures a link-local address from this range, enabling essential neighbour discovery and stateless address autoconfiguration processes.

Why this answer

IPv6 link-local addresses come from FE80::/10. They are valid only on the local link and are commonly used for neighbor discovery and routing adjacency formation.

Exam trap

Don't confuse link-local prefixes with global unicast or multicast prefixes. Remember, link-local addresses are only valid within the local link.

Why the other options are wrong

A

The prefix FC00::/7 is designated for Unique Local Addresses (ULAs) in IPv6, not link-local addresses. Link-local addresses specifically use the FE80::/10 prefix.

C

C: 2000::/3 is incorrect because it designates global unicast addresses, not link-local addresses, which are specifically defined by the prefix FE80::/10.

D

D is incorrect because FF00::/8 is reserved for multicast addresses in IPv6, not link-local addresses. Link-local addresses specifically use the FE80::/10 prefix.

When would these options actually be correct?

A

If the exam question asked for the prefix used for Unique Local Addresses in IPv6, then FC00::/7 would be the correct answer. For example, a question could specify the type of address used for private communication within a site.

C

If the question asked for the prefix used for global unicast addresses in IPv6, option C would be correct, as it identifies the range of addresses that are routable on the internet.

D

If the question asked about the prefix used for multicast addresses in IPv6, then D would be the correct answer. For example, a question could state, 'Which IPv6 prefix is designated for multicast communication?'

Why candidates pick the wrong answer

A

Candidates might be tempted by this option due to its similarity in format to other IPv6 prefixes and a general understanding of IPv6 address types, leading to confusion between link-local and unique local addresses.

C

Candidates may choose this option due to confusion between different IPv6 address types, as 2000::/3 is commonly associated with public addressing, leading to a misinterpretation of the question's focus on link-local addresses.

D

Candidates may choose D because they recognize FF00::/8 as a notable IPv6 prefix and might confuse multicast with link-local addressing due to their shared relevance in network communications.

1206
MCQhard

On a broadcast multiaccess segment, R3 has an OSPF priority of 255, but it is in the DROTHER state. Which explanation best fits OSPF behavior?

A.DR election is nonpreemptive on broadcast networks
B.A router cannot become DR if it uses a loopback router ID
C.OSPF priority works only on point-to-point links
D.R3's priority is lower than the current DR's priority
AnswerA

DR/BDR election is nonpreemptive on broadcast multiaccess networks: once the DR and BDR are elected, they remain in those roles until they fail or the OSPF process/interface is reset. Increasing a router's OSPF priority after the election (as with R3) does not force a new election, so the existing DR stays active even if R3 now has a higher priority. To replace the DR, you must clear the OSPF process or reload the router, not just adjust priority.

Why this answer

On broadcast networks, OSPF DR and BDR election is not preemptive. If a DR is already elected, giving another router a higher priority later does not force a new election unless the current DR goes down or OSPF is reset on the segment.

Exam trap

A common exam trap is assuming that increasing a router's OSPF priority after the DR election will cause it to immediately become the new DR. Many candidates mistakenly believe OSPF DR election is preemptive and that the router with the highest priority always becomes DR instantly. However, OSPF DR election on broadcast networks is nonpreemptive, meaning the current DR remains until it fails or OSPF adjacency resets.

This misunderstanding can lead to incorrect answers about why a router with a higher priority remains DROTHER, as in the case of R3 in the question.

Why the other options are wrong

D

This distractor assumes the election is based on current priority values, but OSPF DR election is nonpreemptive; even if R3's priority is higher, it will not become DR unless the current DR fails.

When would these options actually be correct?

B

In a scenario where the question specifies that OSPF is configured to use loopback interfaces exclusively for router IDs and that the DR election process is limited to routers with physical interfaces only, this option would be correct, as it would imply that a router using a loopback ID cannot become DR.

C

If the question specified a scenario where OSPF priority settings were only applicable to point-to-point links and did not mention broadcast networks, then this option could be correct. For example, a question could ask about OSPF behavior in a purely point-to-point topology, where priority settings determine the DR election.

D

In a different question setup where the scenario specifies that only routers in area 1 can participate in DR elections, this option would be correct. For example, if the question stated that R3 is in area 0 while other routers are in area 1, it would not be eligible to become DR.

Why candidates pick the wrong answer

B

Candidates may find this option tempting because they might confuse the role of router IDs with OSPF DR election, leading them to believe that the type of router ID could impact the ability to become DR.

C

Candidates may be misled by the specific mention of OSPF priority, thinking it is a unique characteristic of point-to-point links, leading them to overlook its applicability in broadcast environments.

D

Candidates might choose this option due to a misunderstanding of OSPF area functions and their impact on router roles, leading them to believe that area membership directly affects DR election eligibility.

1207
MCQhard

A network engineer notices that a new switch, SW3, was connected to port GigabitEthernet0/1 on SW1, but the port immediately went into an err-disabled state. The network uses Rapid PVST+ with BPDU Guard enabled globally on all access ports. The engineer checks the logs and sees 'bpduguard error detected' messages. What is the most likely cause of the err-disabled state?

A.The port is configured as an access port, but BPDU Guard should be disabled on all access ports.
B.A BPDU was received on port GigabitEthernet0/1, triggering BPDU Guard.
C.Configure Root Guard on the interface to prevent the err-disabled state.
D.Enable Loop Guard on the interface to prevent the err-disabled state.
AnswerB

BPDU Guard is a security feature that deliberately places a port into an err-disabled state when a BPDU is received on a port where BPDU Guard is enabled, typically on an access port configured with PortFast. The port GigabitEthernet0/1 transitioning to err-disabled indicates that it received an unexpected BPDU, which suggests another switch was connected to that port. By immediately error-disabling the port, BPDU Guard prevents the unauthorized device from participating in spanning tree and disrupting the topology. This explanation directly matches the observed behavior and is the correct root cause.

Why this answer

The err-disabled state is caused by BPDU Guard triggering when a BPDU is received on an access port. Option A is incorrect because BPDU Guard is intentionally enabled on access ports to prevent unauthorized switches from joining the network. Option C is wrong because Root Guard prevents a port from becoming the root, not from receiving BPDUs.

Option D is wrong because Loop Guard prevents loops on blocked ports in case of unidirectional links, not relevant to BPDU reception.

Exam trap

Cisco often tests the confusion between BPDU Guard, Root Guard, and Loop Guard; candidates may incorrectly attribute the err-disable to Root Guard or Loop Guard, but the true cause is receiving a BPDU on a BPDU-Guard-enabled port.

Why the other options are wrong

A

BPDU Guard is designed to be enabled on access ports to protect against unauthorized switches, so disabling it on all access ports would defeat its purpose.

C

Root Guard prevents a port from becoming the root bridge, but does not block BPDU reception that causes err-disable with BPDU Guard.

D

Loop Guard detects and prevents loops on blocked ports due to unidirectional links, not related to the BPDU Guard err-disable mechanism.

1208
PBQhard

You are connected to R1 via the console. R1 is the DHCP server for the 192.168.50.0/24 LAN. Configure DHCP on R1 to assign addresses from 192.168.50.10 to 192.168.50.200, with default gateway 192.168.50.1 and DNS server 8.8.8.8. Also, configure R1 to act as a DHCP relay agent for the 10.0.0.0/30 link to reach a remote DHCP server at 203.0.113.10. Then, troubleshoot and fix a misconfiguration that causes clients on VLAN 50 to not receive IP addresses.

Network Topology
G0/0:192.168.50.1/24G0/1:10.0.0.1/30linkR1VLAN 50 clientsRemote DHCP server at

Hints

  • Check the excluded-address range — it may be too large.
  • A helper-address on the same subnet as the DHCP server is not needed.
  • The relay agent must be configured on the interface that receives the client broadcasts.
A.[CORRECT] The DHCP pool is misconfigured: the excluded-address range covers most of the pool (192.168.50.1 through 192.168.50.200), but leaves 192.168.50.201-254 assignable, violating the requirement. The correct configuration should exclude 192.168.50.1-9 (gateway) and 192.168.50.201-254 (upper end). The 'ip helper-address' on GigabitEthernet0/0 is unnecessary because R1 itself is the DHCP server for that subnet; it should be removed. The relay agent configuration is missing on the interface facing the remote DHCP server—'ip helper-address 203.0.113.10' should be added to GigabitEthernet0/1.
B.The DHCP pool is misconfigured: the excluded-address range should be 192.168.50.1 192.168.50.9, but the helper-address on GigabitEthernet0/0 is correct because it forwards DHCP requests to the remote server. The relay agent configuration is missing on GigabitEthernet0/1.
C.The DHCP pool is correctly configured with excluded-address 192.168.50.1 192.168.50.9. The issue is that the 'ip helper-address' on GigabitEthernet0/1 is missing; it should be added to forward requests to the remote server. Additionally, the 'ip helper-address' on GigabitEthernet0/0 is correct because it forwards requests from VLAN 50 to the remote server.
D.The DHCP pool is misconfigured: the excluded-address range should be 192.168.50.1 192.168.50.9. The 'ip helper-address' on GigabitEthernet0/0 should be removed. The relay agent configuration is correct because 'ip helper-address 203.0.113.10' is already configured on GigabitEthernet0/1.
AnswerA
solution
! R1
no ip dhcp excluded-address 192.168.50.1 192.168.50.200
ip dhcp excluded-address 192.168.50.1 192.168.50.9
interface GigabitEthernet0/0
no ip helper-address 203.0.113.10
exit
interface GigabitEthernet0/1
ip helper-address 203.0.113.10
exit

Why this answer

The DHCP pool is misconfigured: the excluded-address range of 192.168.50.1 through 192.168.50.200 covers most of the pool, but leaves addresses 192.168.50.201 to 192.168.50.254 assignable, which violates the requirement to assign addresses only from 192.168.50.10 to 192.168.50.200. To meet the requirement, you must exclude both the lower range (192.168.50.1 to 192.168.50.9, reserving the gateway) and the upper range (192.168.50.201 to 192.168.50.254). Additionally, the 'ip helper-address' on GigabitEthernet0/0 is unnecessary because R1 itself is the DHCP server for that subnet; it should be removed.

The relay agent configuration is missing on the interface facing the remote DHCP server—'ip helper-address 203.0.113.10' should be added to GigabitEthernet0/1 so that broadcasts from the 10.0.0.0/30 subnet are forwarded.

Exam trap

A single 'ip dhcp excluded-address' range does not limit the DHCP pool to only the desired contiguous range; you must explicitly exclude all addresses you do not want assigned, even those at the upper end. Ensure you create multiple excluded-address ranges when the pool is not contiguous.

Why the other options are wrong

B

The specific factual error is that a helper-address should not be configured on an interface where the router itself is the DHCP server for that subnet.

C

The specific factual error is that the helper-address on the LAN interface is not needed and would cause issues, and the excluded-address range is actually correct in this option, but the question's misconfiguration is the excluded-address being too broad.

D

The specific factual error is that the helper-address on the interface facing the remote server is not configured, so DHCP broadcasts from the 10.0.0.0/30 subnet will not be forwarded.

Why candidates pick the wrong answer

B

Candidates might think that a helper-address is always needed to forward DHCP broadcasts, but they forget that the router can act as the server locally.

C

Candidates might focus only on the relay agent configuration and overlook the excluded-address misconfiguration, thinking the helper-address on G0/0 is needed for the remote server.

D

Candidates might assume that the relay agent configuration is already in place because it is a common task, but they fail to verify that it is actually missing.

1209
MCQmedium

PCs in VLAN 30 on SwitchA cannot reach servers in VLAN 30 on SwitchB. All other VLANs work across the trunk. What is the most likely cause?

A.The native VLAN is mismatched between the switches.
B.VLAN 30 should be configured as the native VLAN on both ends.
C.SwitchB must use ISL instead of 802.1Q.
D.VLAN 30 is not allowed on the trunk from SwitchA.
AnswerD

This is correct because the exhibit explicitly shows that VLAN 30 is absent from the allowed VLAN list on the trunk interface on SwitchA. For 802.1Q trunking, a VLAN must be permitted on both sides of the link; if it is missing from SwitchA's allowed list, that switch will not forward frames for VLAN 30 onto the trunk, breaking connectivity to the servers. The other VLANs are allowed and therefore work, isolating the issue to the missing VLAN 30 entry.

Why this answer

The trunk is up and carrying multiple VLANs, but VLAN 30 is missing from the allowed list on one side. Since SwitchA and SwitchB both need to permit VLAN 30 on the trunk, if SwitchA's allowed VLAN list does not include VLAN 30, traffic for that VLAN cannot cross. Native VLAN mismatch or ISL vs 802.1Q issues would affect all VLANs, not just VLAN 30.

Thus, the most likely cause is that VLAN 30 is not allowed on the trunk from SwitchA.

Exam trap

Be cautious of assuming native VLAN mismatches or protocol issues when the problem is specific to the allowed VLAN list.

Why the other options are wrong

A

This option is wrong because a native VLAN mismatch would typically affect all VLANs across the trunk, not just VLAN 30. In this scenario, only VLAN 30 is experiencing connectivity issues, indicating a different problem.

B

This option is wrong because configuring VLAN 30 as the native VLAN does not directly affect the ability of PCs in VLAN 30 on SwitchA to communicate with servers in VLAN 30 on SwitchB, especially if VLAN 30 is already properly configured on both switches.

C

SwitchB using ISL instead of 802.1Q is not relevant to the connectivity issue between VLAN 30 on SwitchA and SwitchB. The problem is likely due to VLAN 30 not being allowed on the trunk, not the encapsulation method used.

When would these options actually be correct?

A

In a different question where multiple VLANs are configured on a trunk, and the question specifies that the native VLAN is set differently on each switch, a native VLAN mismatch could cause communication failures across all VLANs, making this option correct.

B

In a different scenario where the question specifies that VLAN 30 is intended to be the native VLAN for both switches, and the native VLAN configuration is incorrect, this option would be correct. For example, if the question states that VLAN 30 is the native VLAN but it is not configured as such on one of the switches, it would lead to communication issues.

C

If the question specified that VLAN 30 was configured on both switches but that the trunk link was limited to only supporting ISL encapsulation, then stating that SwitchB must use ISL instead of 802.1Q would be correct. This would imply a compatibility issue between the two encapsulation methods.

Why candidates pick the wrong answer

A

Candidates might choose this option due to a common misconception that native VLAN mismatches are a frequent cause of VLAN connectivity issues, leading them to overlook the specific details of the question.

B

Candidates may choose this option due to a misunderstanding of native VLANs and their role in trunking, leading them to believe that any VLAN must be set as native to function correctly across trunks.

C

Candidates may choose this option due to a common misconception that encapsulation types directly affect VLAN communication, leading them to overlook the specific trunk configuration issue presented in the question.

1210
MCQmedium

Users on VLAN 20 are not receiving IPv4 addresses from the centralized DHCP server at 10.50.0.10. Users in other VLANs are working normally. Based on the exhibit, which change should fix the issue for VLAN 20 clients?

A.Change the helper address on interface Vlan20 to 10.50.0.10.
B.Convert the VLAN 20 user ports to trunk mode.
C.Configure a default gateway on the user PCs manually.
D.Disable DHCP snooping on VLAN 20.
AnswerA

The DHCP server is not on VLAN 20, so the router interface Vlan20 must use the ip helper-address command to forward DHCP client broadcasts as unicasts to the actual DHCP server at 10.50.0.10. Without a correctly configured helper address, the DHCP messages never leave the local VLAN and clients remain unaddressed. This is the standard fix for a DHCP relay problem.

Why this answer

The SVI for VLAN 20 is forwarding DHCP requests to the wrong helper address. DHCP relay depends on the Layer 3 interface for that VLAN sending client broadcasts to the correct server. Trunks, access ports, and the DHCP pool name on the server are not the first issue shown here.

DHCP snooping can filter DHCP server replies on untrusted ports, but since other VLANs are working and no trust misconfiguration is indicated, the root cause is the incorrect ip helper-address on Vlan20.

Exam trap

A frequent exam trap is assuming that user ports must be trunks or that disabling DHCP snooping will fix DHCP address assignment issues. In reality, user ports should remain in access mode to maintain VLAN membership, and DHCP snooping is unrelated to this specific forwarding problem because the exhibit shows a misconfigured helper address while other VLANs function normally. Another common mistake is thinking that manually configuring a default gateway on clients solves DHCP problems, but DHCP discovery requires proper relay configuration on the Layer 3 interface.

Misconfiguring or omitting the ip helper-address on the VLAN interface causes DHCP requests to fail, which is the core issue here.

Why the other options are wrong

D

Disabling DHCP snooping is unnecessary because the other VLANs work, and the scenario does not indicate a trust misconfiguration; the real problem is the incorrect helper address on Vlan20.

When would these options actually be correct?

B

In a different scenario, if the question stated that VLAN 20 clients were connected to a switch port configured as an access port and needed to communicate with multiple VLANs, converting the user ports to trunk mode could be the correct solution to allow DHCP traffic to traverse between VLANs.

C

In a different scenario where the question states that VLAN 20 clients are unable to communicate with the DHCP server due to incorrect routing or subnetting, manually configuring a default gateway on the user PCs could resolve the issue by ensuring they can reach the DHCP server's subnet.

D

In a scenario where a question asks about troubleshooting DHCP issues and indicates that DHCP snooping is incorrectly blocking legitimate DHCP traffic from a server, disabling DHCP snooping could be the correct action to allow clients to receive IP addresses. This would be applicable if the configuration was preventing legitimate DHCP responses.

Why candidates pick the wrong answer

B

Candidates may choose this option because they associate trunking with VLAN communication and believe that enabling trunking would resolve connectivity issues, overlooking the specific requirement for DHCP relay configuration.

C

Candidates may choose this option because they recognize that a default gateway is essential for network communication and might assume that configuring it on user PCs could resolve connectivity issues without considering the specific context of DHCP relay configurations.

D

Candidates might choose this option because they recognize DHCP snooping as a common security feature that can interfere with DHCP operations, leading them to believe that disabling it could resolve connectivity issues without fully understanding the specific context of the problem.

1211
MCQmedium

Two switches are configured to form an EtherChannel, but the bundle never comes up. Which explanation best describes this scenario?

A.The switches are using different native VLANs.
B.LACP active on one side is incompatible with mode on on the other side.
C.Both sides must use PAgP desirable mode.
D.The interfaces must be configured as routed ports first.
AnswerB

LACP active mode actively sends LACPDUs to negotiate the bundle, while 'mode on' forces the channel statically without sending any negotiation frames. Because the 'on' side never responds to LACP, the active side cannot establish a working partner and the EtherChannel fails to form. The mismatch is a fundamental protocol/config mode incompatibility, not a wiring or VLAN issue.

Why this answer

One side is using LACP active mode and the other side is forcing a static channel-group with mode on. Those modes are not compatible. LACP needs active or passive on both sides, while PAgP uses desirable or auto, and static mode on expects a manual bundle on the other side.

Exam trap

Ensure you match the correct protocol and mode on both sides of the link; mixing protocols or incompatible modes will prevent channel formation.

Why the other options are wrong

A

This option is wrong because different native VLANs do not prevent an EtherChannel from forming; they can still establish a link if other configurations are compatible. The primary issue in this scenario is related to LACP mode mismatches.

C

This option is incorrect because EtherChannel can use either PAgP or LACP for negotiation, and both protocols can operate independently of each other. The requirement for both sides to use PAgP in desirable mode is not a necessity for EtherChannel to function.

D

This option is wrong because EtherChannel can be configured on switch ports without needing to convert them to routed ports. Routed ports are not necessary for EtherChannel to function, as it operates at Layer 2.

When would these options actually be correct?

A

In a different question, if the context involved troubleshooting a trunk link where the native VLANs on both switches were indeed mismatched, this option would be correct. For example, if the question specified that the EtherChannel was configured for trunking and the native VLANs were different, it could lead to a failure in establishing the trunk.

C

In a different scenario where the question specifies that both switches are configured to use PAgP, and one switch is set to 'desirable' mode while the other is set to 'auto', this option would be correct. The question would need to focus on PAgP specifically, rather than LACP.

D

In a different scenario where the question specifies that the switches are intended to connect as routed ports for Layer 3 communication, and the exam asks about the prerequisites for establishing an EtherChannel in that context, this option would be correct.

Why candidates pick the wrong answer

A

Candidates may choose this option because they recall that native VLAN mismatches can cause issues in VLAN communication, leading them to mistakenly believe it would also affect EtherChannel formation.

C

Candidates may choose this option due to a common misconception that both ends of an EtherChannel must use the same protocol, leading them to believe that PAgP modes are strictly required for successful configuration.

D

Candidates may find this option tempting because they might confuse EtherChannel configurations with routed port requirements, leading them to believe that all interfaces must be Layer 3 before forming a channel.

1212
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure an IPv4 static address on a Windows host, generate an IPv6 EUI-64 address on a Cisco router, verify the router's IPv6 EUI-64 address, and confirm connectivity from the Windows host.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps
Order
1Step 1
2Step 2
3Step 3
4Step 4

Why this order

The correct order is: first set a static IPv4 address on the Windows host to establish its network settings, then configure the IPv6 EUI-64 address on the Cisco router to enable IPv6, then verify the generated EUI-64 address on the router to ensure correct configuration, and finally confirm connectivity from the Windows host to the router to validate end-to-end communication. This sequence logically progresses from configuration to verification to testing.

Exam trap

Candidates often confuse the order of configuration and verification steps. Remember that configuration always comes before verification, and the final step is always a connectivity test from the end host.

1213
Multi-Selectmedium

Which two statements accurately describe a default gateway from a host perspective?

Select 2 answers
A.It is the next-hop path a host uses for destinations outside the local subnet.
B.It is typically the IP address of a local router or Layer 3 interface on the same subnet.
C.It replaces the need for a subnet mask.
D.It is the same thing as a DNS server.
E.It is used only for ARP broadcasts.
AnswersA, B

A default gateway is the designated next-hop router that a host uses to send IP packets to destinations outside its local subnet. The host compares its destination IP against its own subnet mask; if the destination is not local, it frames the packet for the gateway's MAC address, while keeping the final destination IP. Thus, the gateway is the exit point for all off-subnet traffic.

Why this answer

A default gateway is the local router or Layer 3 interface that a host uses for traffic destined beyond its own subnet. In plain language, the host uses the gateway when the destination is not local. The default gateway does not replace the host’s own IP address or subnet mask; it complements them by providing the next-hop path for remote communication.

This is a foundational host-networking concept because many connectivity issues come from misunderstanding what the gateway actually does. The two correct answers are the ones that describe remote-traffic forwarding and the local next-hop role of the gateway.

Exam trap

Avoid confusing the gateway's role with local traffic handling or address replacement. Focus on its function in remote communication.

Why the other options are wrong

C

This option is wrong because a default gateway does not replace the need for a subnet mask; both are essential for proper IP communication. The subnet mask defines the network portion of an IP address, while the default gateway routes traffic to external networks.

D

This option is wrong because a default gateway and a DNS server serve different purposes; the default gateway routes traffic outside the local subnet, while a DNS server resolves domain names to IP addresses.

E

This option is wrong because a default gateway is not limited to ARP broadcasts; it is used for routing packets to destinations outside the local subnet, which involves more than just ARP communication.

When would these options actually be correct?

C

In a question that asks about network configuration in a hypothetical scenario where a new protocol or technology eliminates the need for subnet masks, this option could be correct. For example, if the exam presented a futuristic networking model where addressing is simplified, making subnet masks obsolete, this statement would apply.

D

In a question asking for the definition of network services, if it stated that both the default gateway and DNS server are essential for network communication, option D could be correct in the context of discussing their roles in enabling host connectivity.

E

In a question asking about the functions of ARP in a network, where the focus is solely on how devices communicate at the data link layer, one might correctly state that a default gateway is used for ARP broadcasts to resolve IP addresses to MAC addresses for outbound traffic.

Why candidates pick the wrong answer

C

Candidates may find this option tempting because they might confuse the roles of the default gateway and subnet mask, thinking that one could functionally replace the other in simplifying network configurations.

D

Candidates may confuse the roles of network components, mistakenly thinking that since both are critical for internet access, they must be interchangeable or related in function.

E

Candidates may choose this option due to a misunderstanding of ARP's role in networking, conflating the function of a default gateway with the process of address resolution, leading to confusion about their distinct purposes.

1214
MCQhard

Refer to the exhibit. A network engineer is troubleshooting intermittent connectivity between a branch router and the upstream switch. The switch port is manually configured for full-duplex, and the Ethernet cable has been tested and is working properly. The engineer runs the show interfaces GigabitEthernet0/0 command on the router and receives the output shown. Based on the output, what is the most likely cause of the problem?

A.The switch port is configured for half-duplex instead of the expected full-duplex.
B.The cable is faulty, causing excessive late collisions and CRC errors.
C.The router interface is operating in half-duplex while the switch port is full-duplex, causing a duplex mismatch.
D.The excessive input errors are a result of a broadcast storm on the network.
AnswerC

The output shows 'Half-duplex, 1000Mb/s' and reports 17 late collisions and 23 CRC errors. With the switch known to be full-duplex, this is a classic duplex mismatch scenario, where the full-duplex switch transmits without sensing the medium, while the half-duplex router interprets simultaneous traffic as collisions (many of them late because the switch may start transmitting after the router has already begun its frame).

Why this answer

The output shows the router interface is operating in half-duplex (as indicated by 'Half-duplex' in the show interfaces output), while the switch port is manually configured for full-duplex. This duplex mismatch causes the router to use CSMA/CD and detect collisions, while the switch transmits without collision detection, leading to late collisions, CRC errors, and intermittent connectivity. The correct fix is to set both sides to the same duplex setting, ideally full-duplex.

Exam trap

Cisco often tests duplex mismatch by showing output with late collisions and CRC errors, and the trap here is that candidates may blame the cable (Option B) or assume the switch port is half-duplex (Option A), when the real issue is the router interface operating in half-duplex against a full-duplex switch port.

Why the other options are wrong

A

Users often think any collision indicator points to both sides being half-duplex, ignoring the known switch configuration.

B

Late collisions are commonly associated with physical layer issues, leading candidates to assume a cable problem even when explicitly ruled out.

D

Candidates see input errors and CRC and prematurely conclude a loop or broadcast storm, overlooking that the output shows no broadcast activity and contains late collisions specific to duplex issues.

1215
Multi-Selectmedium

Which two statements accurately describe good design thinking for wireless guest access?

Select 2 answers
A.Guest access should normally be isolated from internal corporate resources.
B.Guest access policies should usually reflect lower trust than employee access.
C.Guest WLANs should avoid all security to make access easier.
D.Guest WLANs should automatically use the same permissions as internal employee WLANs.
E.Guest access means the AP no longer needs controller coordination.
AnswersA, B

Guest access should normally be isolated from internal corporate resources because guests are untrusted endpoints. In a proper design, guest traffic is placed in a separate VLAN or VRF, and a firewall or access control list (ACL) restricts it to internet-only connectivity, blocking any reachability to internal subnets, servers, or employee devices. This segmentation prevents compromised or malicious guest devices from pivoting into the corporate network.

Why this answer

Good guest-access design is based on isolation and appropriate policy. In practical terms, guest users should normally be separated from internal corporate resources, and their access should align with the limited purpose of guest connectivity. The goal is not to give them the same trust level as managed internal users.

This is about segmentation and policy, not about disabling the WLAN or eliminating security.

Exam trap

Don't assume guest access should mirror internal access policies; guests should have more restricted access.

Why the other options are wrong

C

This option is wrong because good design thinking for guest access requires implementing security measures to protect the network and its resources, even for guests. Completely avoiding security compromises the network's integrity and exposes it to potential threats.

D

This option is wrong because guest WLANs should have distinct permissions to ensure that guests do not have access to sensitive internal resources, which could lead to security breaches.

E

This option is wrong because guest access typically requires controller coordination to manage policies, monitoring, and security effectively, ensuring that guest traffic is properly segmented and controlled.

When would these options actually be correct?

C

In a scenario where the exam question focuses on a specific type of public Wi-Fi network, such as an open access point in a coffee shop, where the primary goal is to provide easy access for customers without any security measures. Here, the context would justify the option as correct.

D

In a scenario where the exam question asks about a network design for a small business with minimal security concerns and a fully trusted environment, it could be appropriate for guest WLANs to share permissions with internal employee WLANs, assuming all users are known and vetted.

E

In a question focused on a specific type of wireless network architecture where lightweight access points operate independently without a controller, option E could be correct. For example, if the question specifies a scenario with a fully autonomous network setup designed for temporary events, where centralized control is not feasible.

Why candidates pick the wrong answer

C

Candidates may find this option tempting due to the misconception that easier access translates to better user experience, especially in environments where quick connectivity is prioritized over security considerations.

D

Candidates may choose this option due to a misunderstanding of network segmentation, believing that simplifying access for guests by aligning permissions with internal users is a practical approach to ease management and user experience.

E

Candidates might choose this option due to a misunderstanding of network architectures, believing that simplifying guest access by removing controller coordination would enhance user experience without considering security implications.

1216
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure single‑area OSPFv2 on a router, advertise the 192.168.10.0/24 and 10.0.0.0/24 networks in area 0, and set the GigabitEthernet0/0 interface as passive.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps
Order
1Step 1
2Step 2
3Step 3
4Step 4
5Step 5
6Step 6

Why this order

The correct sequence is: (1) Enter global configuration mode with 'configure terminal' – this is required before any configuration commands. (2) Initiate the OSPF process with 'router ospf 1' – this places the CLI into OSPF router configuration mode where the remaining commands are issued. (3) Advertise the 192.168.10.0/24 network in area 0 – the 'network' command must be issued under OSPF router mode to inject the connected network into OSPF. (4) Advertise the 10.0.0.0/24 network – a second 'network' statement; the order of network commands is interchangeable but they must be configured before setting passive interfaces in a logical workflow. (5) Configure GigabitEthernet0/0 as a passive interface – this prevents OSPF Hello packets and neighbor adjacency on that interface while still advertising its subnet, and it is configured under OSPF router mode. (6) Return to privileged EXEC mode with 'end' – exits configuration mode and returns to the enable prompt. While setting a passive interface before the network statement does not break the configuration, Cisco documentation suggests adding networks first to clearly define which interfaces participate in OSPF before applying passive-interface restrictions.

1217
MCQhard

A network team wants visibility into which flows are consuming the most bandwidth between internal subnets. Which technology is most directly associated with that goal?

A.NetFlow
B.Syslog
C.DHCP relay
D.PortFast
AnswerA

NetFlow is a network telemetry protocol that captures metadata about IP traffic flows, including source/destination IP addresses, ports, ToS, and byte/packet counts. By exporting these flow records to a collector, administrators can identify which applications, hosts, or conversations are consuming the most bandwidth. This makes NetFlow the appropriate technology for flow-level visibility and traffic consumption analysis.

Why this answer

NetFlow provides visibility into traffic flows, allowing administrators to identify which flows (e.g., between internal subnets) are consuming the most bandwidth by showing source/destination, protocols, and traffic volume. Syslog only records system logs and events, not flow-level data. DHCP relay forwards DHCP broadcasts across subnets but offers no traffic analysis.

PortFast is an STP optimization that speeds up port transition to forwarding; it does not monitor bandwidth usage.

Exam trap

A frequent exam trap is mistaking Syslog or DHCP relay as solutions for traffic flow visibility. Syslog only records system events and error messages, not detailed traffic usage. DHCP relay simply forwards DHCP requests and does not analyze bandwidth.

Another trap is confusing PortFast, which is an STP feature to speed up port activation, with traffic monitoring technologies. Candidates must recognize that only NetFlow provides granular flow data needed to identify bandwidth consumption between internal subnets, making it the correct choice.

Why the other options are wrong

B

Syslog is incorrect because it only records system events, error messages, and notifications. It does not provide detailed traffic flow or bandwidth usage information, so it cannot help identify which flows consume the most bandwidth.

C

DHCP relay is incorrect as its function is to forward DHCP broadcast requests from clients to DHCP servers across different subnets. It does not analyze or report on traffic flows or bandwidth consumption.

D

PortFast is incorrect because it is a Spanning Tree Protocol feature that allows edge ports to transition quickly to the forwarding state. It has no role in traffic flow analysis or bandwidth monitoring.

When would these options actually be correct?

B

If the question asked about monitoring and logging network events or troubleshooting network issues, then Syslog would be the correct answer, as it captures logs from devices to help diagnose problems.

C

If the exam question asked about technologies that facilitate the management of IP address allocation and client-server communication in a network, then DHCP relay would be the correct answer. For example, a question might ask which technology helps in extending DHCP services across multiple subnets.

D

If the question asked about optimizing switch port performance in a network with rapid device connections, PortFast would be the correct answer. For example, a scenario focusing on reducing connection delays for devices in a dynamic environment could make this option valid.

Why candidates pick the wrong answer

B

Candidates may confuse Syslog with network monitoring tools, thinking that any logging mechanism can provide insights into bandwidth usage, leading them to select it despite its specific function.

C

Candidates may confuse DHCP relay with network monitoring tools, thinking it relates to traffic management due to its role in facilitating communication across subnets, leading them to select it mistakenly.

D

Candidates might confuse PortFast with network performance optimization features, mistakenly believing it relates to monitoring or managing bandwidth usage, especially if they are familiar with its role in enhancing connectivity speed.

1218
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure Root Guard on designated ports, Loop Guard on non-designated ports, and BPDU Guard on PortFast ports, and to recover a port that enters err-disabled due to a BPDU guard violation.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps
Order
1Step 1
2Step 2
3Step 3
4Step 4

Why this order

Root Guard on designated, Loop Guard on non-designated, then BPDU Guard on PortFast; recovery requires interface reset after violation.

Exam trap

Candidates often confuse the port roles for Root Guard and Loop Guard, or think that disabling the protection feature will recover an err-disabled port. Remember: Root Guard is for designated ports, Loop Guard for non-designated, and BPDU Guard for PortFast. Err-disabled recovery requires manual reset or global errdisable recovery configuration.

Why candidates pick the wrong answer

B

Candidates might think that re-enabling the feature that caused the violation would recover the port, or they may confuse the order of configuration steps.

C

Candidates might know that errdisable recovery can automatically recover ports, and they might think that is the intended recovery step, but the question expects a manual reset.

D

Candidates might think that disabling the feature that caused the violation would allow the port to come back up, but err-disabled requires manual intervention.

1219
MCQhard

A network administrator is troubleshooting an issue where hosts in the 192.168.20.0/24 subnet cannot reach the Internet, while hosts in 192.168.10.0/24 can. The router is configured for PAT overload using a dynamic pool on the outside interface. The administrator collects the configuration shown in the exhibit. What is the most likely cause of the connectivity problem for the 192.168.20.0/24 subnet?

A.The wildcard mask in access list 20 is incorrect; it matches only the network address.
B.The NAT pool does not have enough IP addresses to support both subnets.
C.Interface GigabitEthernet0/2 is missing the ip nat inside command.
D.Access list 10 is incorrectly applied to the NAT pool, causing a conflict.
AnswerA

Access list 20 uses wildcard mask 0.0.0.0, which requires an exact match on all 32 bits; therefore it matches only the host address 192.168.20.0, not the entire subnet. For NAT to translate all hosts in the 192.168.20.0/24 network, the wildcard mask must be 0.0.0.255, causing the router to ignore the last octet and match addresses from .1 to .254. As written, only traffic sourced from 192.168.20.0 (which is practically never used as a source IP) would be translated, so all other hosts in that subnet fail to access the outside network.

Why this answer

The issue is that access list 20, used to define which internal addresses are eligible for NAT, has a wildcard mask of 0.0.0.0. This wildcard mask matches only the exact address 192.168.20.0, not the entire 192.168.20.0/24 subnet. For a /24 subnet, the correct wildcard mask should be 0.0.0.255, which would match all addresses from 192.168.20.1 to 192.168.20.254.

Because the ACL matches only the network address (192.168.20.0), no host traffic from that subnet is translated, breaking Internet connectivity.

Exam trap

Cisco often tests the distinction between matching the network address versus matching the host range in ACLs used for NAT, where candidates incorrectly assume that using the network address with a wildcard mask of 0.0.0.0 will match all hosts in the subnet.

Why the other options are wrong

B

NAT pool size is not a limiting factor with PAT overload; a single address can serve thousands of hosts.

C

The interface is correctly configured for NAT inside.

D

Applying multiple access lists to the same pool is allowed and does not create a conflict.

1220
MCQhard

Why is idempotency valuable in network automation?

A.It guarantees every API call will use TCP instead of UDP.
B.It ensures repeated runs converge on the same desired state safely.
C.It encrypts device credentials stored in scripts.
D.It forces the controller to use only one management protocol.
AnswerB

Idempotency ensures that executing the same automation task multiple times produces exactly the same outcome as a single execution, converging on the desired state without adding duplicate entries or reverting changes. In network automation, retries happen due to timeouts or partial failures, and idempotent operations safely reconcile the network to its intended configuration while reducing drift. This property is fundamental to robust automation because it makes the system self-healing and predictable.

Why this answer

Idempotent operations can be applied repeatedly without causing unintended changes once the desired state is already present.

Exam trap

Avoid confusing idempotency with concepts like redundancy or performance enhancements. Focus on its role in maintaining consistent configurations.

Why the other options are wrong

A

This option is incorrect because idempotency does not relate to the transport layer protocols like TCP or UDP; it focuses on the behavior of operations in terms of repeated execution leading to the same outcome.

C

Option C is incorrect because idempotency does not relate to the encryption of device credentials; it refers to the property of operations that can be applied multiple times without changing the result beyond the initial application.

D

Option D is incorrect because idempotency does not dictate the use of a single management protocol; rather, it refers to the property of operations yielding the same result regardless of how many times they are executed.

When would these options actually be correct?

A

If the exam question asked about the characteristics of network protocols and their reliability, a question could state, 'Which transport layer protocol guarantees that data is reliably delivered in the same order it was sent?' In that context, TCP would be the correct answer.

C

If the exam question asked about the benefits of secure coding practices in network automation, specifically focusing on protecting sensitive information, then option C could be correct in the context of discussing how encryption secures device credentials in scripts.

D

In a question focused on network management strategies, if it asked about the benefits of using a single management protocol for consistency and control in network automation, then option D could be correct, as it would emphasize the importance of protocol uniformity.

Why candidates pick the wrong answer

A

Candidates might choose this option due to a misunderstanding of idempotency, confusing it with the reliability features of network protocols, leading them to incorrectly associate it with TCP's guaranteed delivery.

C

Candidates may choose this option due to a misunderstanding of security concepts, conflating idempotency with the need for secure handling of credentials, which is a common concern in network automation.

D

Candidates may be drawn to this option due to a misunderstanding of how network protocols interact with automation processes, mistakenly believing that limiting management protocols inherently leads to idempotent behavior.

1221
Multi-Selectmedium

Which TWO statements accurately describe the behavior and configuration of floating static routes?

Select 2 answers
A.A floating static route is configured with a lower administrative distance than the primary dynamic route.
B.A floating static route uses an administrative distance greater than that of the primary dynamic route.
C.The administrative distance of a floating static route must be less than 1.
D.A floating static route becomes active only when the primary route is removed from the routing table.
E.Floating static routes automatically adjust their administrative distance based on network conditions.
AnswersB, D

This is the fundamental characteristic of a floating static route. By assigning an AD higher than the primary route's AD, the static route becomes less preferred, so it will not appear in the routing table while the dynamic route is alive. A typical example is configuring a static route with AD 150 when OSPF is running at AD 110; the static route only takes over if the OSPF route is withdrawn. This mechanism allows the router to automatically switch to a backup path when the primary path is lost.

Why this answer

A floating static route serves as a backup by being configured with an administrative distance (AD) greater than that of the primary dynamic route, making it less preferred (option B). It remains inactive until the primary route is removed from the routing table, at which point the floating static route is installed (option D). Option A is wrong because it reverses the AD logic—a floating static route uses a higher, not lower, AD.

Option C is incorrect because the AD of a floating static route is typically a value between 1 and 255, not necessarily less than 1. Option E is false because the AD of a floating static route is a fixed configured value and does not change automatically based on network conditions.

Exam trap

Cisco often tests the misconception that a floating static route uses a lower AD to 'float' above the primary route, when in fact it uses a higher AD to remain inactive until the primary route is lost.

Why the other options are wrong

A

A lower AD would make the static route preferred over the dynamic route, not floating.

C

AD values are integers; 0 is directly connected, and 1 is static. A floating static route must be >1 to be less preferred than a static default.

E

AD is a static value set at configuration time; it does not auto-adjust.

1222
MCQhard

A switchport connected to another switch should carry multiple VLANs, but it was manually configured as an access port. What is the most likely operational result?

A.The link will not carry multiple VLANs as intended because an access port handles one VLAN only.
B.The switch automatically converts the access port into a proper trunk.
C.The port becomes a routed Layer 3 interface.
D.The VLANs are summarized into one prefix automatically.
AnswerA

An access port is configured to carry exactly one untagged VLAN—the port's assigned access VLAN—and it strips or rejects tags on ingress/egress. Therefore, traffic from multiple VLANs cannot traverse this inter-switch link, and frames from VLANs other than the access VLAN are dropped or not forwarded as intended. To support multiple VLANs between switches, the port must be configured as a trunk using switchport mode trunk.

Why this answer

An access port is designed to carry only a single VLAN. If the link is intended to carry multiple VLANs, it must be configured as a trunk. The switch will not automatically convert the port to a trunk (B).

The port remains a Layer 2 access port, not a routed Layer 3 interface (C). VLANs are not automatically summarized into a single prefix (D). The most likely result is that the link will not carry multiple VLANs as intended.

Exam trap

Beware of confusing automatic port mode changes with manual configurations. Access ports do not auto-convert to trunk mode.

Why the other options are wrong

B

Switches do not automatically convert an access port to a trunk; manual configuration is required.

C

An access port remains a Layer 2 interface; it does not become a routed Layer 3 interface.

D

VLANs operate at Layer 2 and are not automatically summarized into a single prefix; that would be a routing function.

When would these options actually be correct?

B

In a scenario where a switch is configured with a feature like Dynamic Trunking Protocol (DTP) and the connected device is also set to negotiate trunking, the switch could automatically convert the access port to a trunk. The question would need to specify that DTP is enabled and both switches support it.

C

In a different question scenario where a switchport is configured as a Layer 3 interface, and the context involves routing between VLANs, this option could be correct if the question asks about the behavior of a port set to Layer 3 instead of Layer 2.

D

In a different scenario where a question asks about a Layer 3 switch that automatically summarizes VLANs for routing purposes, this option could be correct. For instance, if the question specifies that the switch is configured to aggregate VLANs for inter-VLAN routing, summarization could occur.

Why candidates pick the wrong answer

B

Candidates may choose this option due to a misunderstanding of how trunking works and the assumption that switches can automatically adjust configurations based on the connected device's capabilities.

C

Candidates may choose this option due to confusion between Layer 2 and Layer 3 functionalities, mistakenly believing that access ports can be converted to routed interfaces under certain conditions.

D

Candidates may find this option tempting because they might confuse the concept of VLAN summarization in routing protocols with the behavior of switchports, leading them to incorrectly believe that access ports can handle multiple VLANs through summarization.

1223
Multi-Selectmedium

Which two statements accurately describe the purpose of least privilege in administration and operations?

Select 2 answers
A.It limits users and administrators to the permissions they actually need.
B.It helps reduce unnecessary exposure and the impact of mistakes or misuse.
C.It means no administrator should ever have any configuration access.
D.It replaces the need for logging and accounting.
E.It exists only on wireless guest networks.
AnswersA, B

Least privilege is a security principle that grants each subject—whether a standard user or an administrator—only the minimum rights required to perform their assigned job function. By scoping privileges to explicit job requirements, the organization reduces the attack surface and prevents privilege escalation that results from standing high-level access. This principle is implemented through role-based access control, where permissions are assigned according to defined roles rather than individual preferences.

Why this answer

Least privilege is about limiting access to what is actually needed. In practical terms, it reduces unnecessary exposure and helps contain the impact of mistakes, misuse, or compromised accounts. It is not about refusing all access. It is about granting enough access to do the job, but not more than that.

This is a central principle in secure administration and role design.

Exam trap

Avoid confusing least privilege with either unrestricted access or complete denial of access.

Why the other options are wrong

C

This option is incorrect because the principle of least privilege does not imply that administrators should have no configuration access; rather, it means they should only have the access necessary to perform their job functions.

D

This option is incorrect because least privilege does not eliminate the need for logging and accounting; instead, it complements these practices by ensuring that access is limited while still requiring oversight and tracking of actions taken by users.

E

This option is incorrect because the principle of least privilege applies to all network environments, not just wireless guest networks. It is a fundamental security concept that should be implemented across all systems and user roles.

When would these options actually be correct?

C

If the exam question were to ask about a security policy that mandates a complete separation of duties, stating that no administrator should have any configuration access could be correct in a context where strict segregation is enforced to prevent unauthorized changes.

D

In a question focused on the principles of security management, asking whether least privilege can negate the need for logging and accounting in a specific context, such as a highly controlled environment where access is strictly monitored, could make this option correct if the premise is that logging is deemed unnecessary due to other security measures.

E

If the exam question specifically asked about security measures applicable only to wireless guest networks, then this option could be correct. For example, a question might state, 'What security principle is primarily focused on limiting access in wireless guest network scenarios?'

Why candidates pick the wrong answer

C

Candidates may choose this option due to a misunderstanding of least privilege, confusing it with the idea of complete access denial, which can lead to the assumption that no access is the safest approach.

D

Candidates may find this option tempting because they might confuse the concept of least privilege with a false sense of security, believing that limiting access alone is sufficient to eliminate the need for monitoring user actions.

E

Candidates might choose this option due to a misunderstanding of the scope of least privilege, mistakenly associating it with specific network types rather than recognizing its broader applicability across all systems.

1224
MCQmedium

An engineer applies this command on an access interface connected to a user PC: switchport port-security violation restrict. What happens if a second unauthorized MAC address appears on the port?

A.The port immediately goes err-disabled.
B.Frames from the unauthorized MAC are dropped and the violation is counted while the port stays up.
C.The switch forwards the traffic but logs a warning.
D.The port transitions to listening and learning states.
AnswerB

In port-security restrict mode, frames from an unauthorized MAC address are silently discarded at the ingress port, and the port's security violation counter is incremented to record the event. Crucially, the access port remains operationally up and continues to forward traffic from all authorized MACs, so normal connectivity is not interrupted. This behavior distinguishes restrict from shutdown (which err-disables the port) and protect (which drops but does not increment the counter).

Why this answer

With restrict mode, the switch drops frames from the violating MAC, increments the violation counter, and can generate notifications. Unlike shutdown mode, the interface stays up. Unlike protect mode, the switch records the violation.

Exam trap

A frequent exam trap is mistaking the restrict violation mode for shutdown mode. Many candidates incorrectly believe that a violation in restrict mode causes the port to go err-disabled immediately, but this behavior only occurs with the shutdown mode. Another common confusion is between restrict and protect modes; protect silently drops unauthorized frames without incrementing violation counters or generating alerts, whereas restrict does both.

Misunderstanding these differences can lead to incorrect answers about port behavior during security violations. Remember, restrict mode blocks unauthorized MAC addresses but keeps the port active and counts violations, which is a key distinction in Cisco port security.

Why the other options are wrong

A

Option A describes the shutdown violation mode behavior, where the port immediately goes err-disabled upon detecting a second unauthorized MAC address. Since the command specifies 'violation restrict', the port does not disable but stays up, so this option is incorrect.

C

Option C is incorrect because port security never forwards traffic from unauthorized MAC addresses. The switch drops such frames to enforce security policies, so forwarding violating traffic is not possible.

D

Option D is incorrect because listening and learning states refer to Spanning Tree Protocol (STP) port states, not port security violation responses. Port security violation modes do not cause STP state changes.

When would these options actually be correct?

A

If the question specified a command that sets the violation mode to 'shutdown' instead of 'restrict', then the correct answer would be that the port goes err-disabled upon detecting a second unauthorized MAC address. This would align with the behavior of the shutdown mode.

C

If the question stated that the command used was 'switchport port-security violation protect', then this option would be correct, as it allows the switch to forward traffic from authorized MAC addresses while dropping frames from unauthorized ones without disabling the port.

D

In a different scenario where the question asks about a switchport configured with 'switchport port-security violation shutdown', the port would indeed transition to err-disabled, but if it were a question about a port security feature that allows learning of new MACs, this option could be correct.

Why candidates pick the wrong answer

A

Candidates may choose this option due to confusion between different port-security violation modes, particularly if they recall that some modes do disable the port, leading to a misinterpretation of the command's effect.

C

Candidates may choose this option because they might confuse the behavior of port security with logging features, thinking that any unauthorized access would trigger a log warning while still allowing traffic to pass.

D

Candidates may find this option tempting because they might confuse port security behavior with Spanning Tree Protocol (STP) states, leading them to think that unauthorized MAC addresses would trigger a state change.

1225
PBQmedium

You are connected to R1 via the console. R1's GigabitEthernet0/0 (10.0.0.1/30) connects to ISP router, and GigabitEthernet0/1 (192.168.1.1/24) connects to the internal LAN. The internal network uses 192.168.1.0/24 and needs to access the internet. Configure NAT overload on R1 so that internal hosts are translated to the IP address of GigabitEthernet0/0 when accessing the internet.

Network Topology
G0/010.0.0.1/30G0/1192.168.1.1/24InternetISPR1LANPCs

Hints

  • Define inside and outside interfaces separately.
  • Use the ACL to identify which traffic to translate.
  • The overload keyword enables PAT.
A.R1(config)# access-list 1 permit 192.168.1.0 0.0.0.255 R1(config)# ip nat inside source list 1 interface GigabitEthernet0/0 overload R1(config)# interface GigabitEthernet0/0 R1(config-if)# ip nat outside R1(config-if)# interface GigabitEthernet0/1 R1(config-if)# ip nat inside
B.R1(config)# access-list 1 permit 192.168.1.0 0.0.0.255 R1(config)# ip nat inside source list 1 interface GigabitEthernet0/1 overload R1(config)# interface GigabitEthernet0/0 R1(config-if)# ip nat outside R1(config-if)# interface GigabitEthernet0/1 R1(config-if)# ip nat inside
C.R1(config)# access-list 1 permit 192.168.1.0 0.0.0.255 R1(config)# ip nat inside source list 1 interface GigabitEthernet0/0 R1(config)# interface GigabitEthernet0/0 R1(config-if)# ip nat outside R1(config-if)# interface GigabitEthernet0/1 R1(config-if)# ip nat inside
D.R1(config)# access-list 1 permit any R1(config)# ip nat inside source list 1 interface GigabitEthernet0/0 overload R1(config)# interface GigabitEthernet0/0 R1(config-if)# ip nat outside R1(config-if)# interface GigabitEthernet0/1 R1(config-if)# ip nat inside
AnswerA
solution
! R1
ip nat inside source list 1 interface GigabitEthernet0/0 overload
interface GigabitEthernet0/0
ip nat outside
interface GigabitEthernet0/1
ip nat inside

Why this answer

NAT overload (PAT) allows multiple internal hosts to share a single public IP by using different source ports. The ACL identifies the internal network, and the interfaces are marked as inside/outside. The 'overload' keyword enables port address translation.

Option B fails because it translates to the wrong interface (GigabitEthernet0/1) instead of the public-facing interface (GigabitEthernet0/0). Option C is missing the required 'overload' keyword, so it performs dynamic NAT without PAT, which is insufficient for multiple hosts. Option D uses an overly broad ACL ('permit any') that does not match only the internal network (192.168.1.0/24) as required by the stem.

Exam trap

The most common traps are: (1) confusing inside and outside interfaces when specifying the NAT source, (2) forgetting the 'overload' keyword for PAT, and (3) using an overly permissive ACL like 'permit any' instead of restricting to the internal network. Always verify interface roles and the ACL scope.

Why the other options are wrong

B

The 'ip nat inside source list' command must specify the outside interface (the one with the public IP) for translation, not the inside interface.

C

NAT overload (PAT) requires the 'overload' keyword to enable port address translation. Without it, the router performs dynamic NAT, which is insufficient for sharing a single public IP among many hosts.

D

The ACL should match only the internal network that requires translation. Using 'permit any' would translate all traffic, including traffic that should not be translated, potentially breaking connectivity or causing security risks.

Why candidates pick the wrong answer

B

Candidates might confuse the inside and outside interfaces, thinking the source list should reference the inside interface because the traffic originates there.

C

Candidates may forget the 'overload' keyword, especially if they are used to configuring static NAT or dynamic NAT without PAT.

D

Candidates might think 'permit any' is simpler and still works, but it is overly permissive and not best practice. They may not realize the importance of restricting NAT to the intended internal network.

1226
MCQhard

A port connected to an end host is configured with PortFast and BPDU Guard. What is the most likely result if a small unmanaged switch is connected and starts sending BPDUs?

A.The port is error-disabled by BPDU Guard.
B.The port automatically becomes the root port.
C.The port is converted into a trunk.
D.The port ignores the BPDU because PortFast disables STP entirely.
AnswerA

BPDU Guard is a PortFast enhancement that places the port into the errdisable state whenever a BPDU is received on an edge port. Since PortFast assumes the port connects to an end host, any incoming BPDU signals a potential bridging loop or switch misconfiguration. The switch immediately shuts down the port to protect the spanning-tree topology, overriding any normal STP processing that might otherwise occur.

Why this answer

The most likely result is that the port is placed into an err-disabled state by BPDU Guard. In practical terms, PortFast tells the switch to treat the interface like an edge port for a normal endpoint, which is why it starts forwarding quickly. BPDU Guard protects that assumption. If the port suddenly receives a spanning-tree BPDU, the switch treats that as a sign that the port is no longer connected to a simple end device.

This combination is common in enterprise access-layer design because it improves user startup time while still protecting the topology. The correct answer is the one that describes the port being shut down automatically when BPDUs appear unexpectedly.

Exam trap

Remember, BPDU Guard disables the port, it doesn't use spanning-tree states like blocking or learning.

Why the other options are wrong

B

This option is wrong because a port configured with PortFast and BPDU Guard will not automatically become the root port when it receives BPDUs; instead, it will be error-disabled due to BPDU Guard's protection mechanism.

C

This option is wrong because a port configured with PortFast does not automatically convert to a trunk port when it receives BPDUs; instead, it remains in access mode. BPDU Guard will cause the port to be error-disabled upon receiving BPDUs, preventing any trunking behavior.

D

This option is wrong because PortFast does not disable Spanning Tree Protocol (STP) entirely; it merely allows the port to transition to the forwarding state immediately without participating in STP calculations. BPDUs are still processed, and BPDU Guard will take action if they are received.

When would these options actually be correct?

B

In a different scenario where a switch is configured without BPDU Guard and is part of a larger network topology, a port could automatically become the root port if it is the lowest-cost path to the root bridge during the Spanning Tree Protocol (STP) convergence process.

C

In a different scenario where a switch port is configured to allow trunking and is explicitly set to negotiate trunking with connected devices, a small unmanaged switch could potentially cause the port to convert to a trunk if it supports dynamic trunking protocols. The question would need to specify that trunking is enabled and that the connected device is capable of sending DTP messages.

D

In a different scenario where a switch port is configured with PortFast but not with BPDU Guard, a question could ask what happens when a small unmanaged switch sends BPDUs. In that case, the port would ignore the BPDUs and remain in the forwarding state, making this option correct.

Why candidates pick the wrong answer

B

Candidates may find this option tempting because they might confuse the behavior of STP with PortFast, thinking that the port's role in the STP topology can change dynamically based on BPDU reception.

C

Candidates may find this option tempting because they might confuse the behavior of PortFast with trunking configurations, mistakenly believing that any BPDU received would trigger a trunk negotiation instead of causing the port to be error-disabled.

D

Candidates may choose this option due to a misunderstanding of PortFast's function, believing it completely disables STP and thus would not react to BPDUs, leading to the assumption that the port would ignore them.

1227
MCQmedium

A network administrator receives a report that a user on a Windows laptop cannot connect to the internet, although other devices on the same subnet are working. The administrator runs `ipconfig` on the laptop and sees an IP address of 169.254.15.22 with a subnet mask of 255.255.0.0 and no default gateway. Based on this output, what is the most likely cause of the connectivity issue?

A.The laptop's DNS server settings are incorrect.
B.The DHCP server is unreachable or not responding to the laptop's DHCP request.
C.The laptop has a static IP address configured that conflicts with another device.
D.The Ethernet cable is faulty or disconnected.
AnswerB

APIPA is assigned when a DHCP client fails to receive a DHCPOFFER after sending DHCPDISCOVER messages. This typically means the DHCP server is down, misconfigured, or the laptop cannot reach it due to a network issue (e.g., VLAN mismatch, switch port problem).

Why this answer

The IP address 169.254.15.22 with a subnet mask of 255.255.0.0 is an Automatic Private IP Addressing (APIPA) address, which Windows assigns when a DHCP client fails to obtain a lease from a DHCP server. The absence of a default gateway confirms that the laptop cannot reach any DHCP server, as APIPA addresses are not routable and are only used for link-local communication. Therefore, the most likely cause is that the DHCP server is unreachable or not responding to the laptop's DHCP request.

Exam trap

Cisco often tests the distinction between APIPA and other IP assignment failures, and the trap here is that candidates may confuse a DHCP failure with a physical layer issue (faulty cable) or a DNS misconfiguration, not realizing that APIPA is a specific Windows behavior triggered only by DHCP unavailability.

Why the other options are wrong

A

The APIPA address indicates a DHCP failure, not a DNS problem.

C

A static IP conflict would not result in an APIPA address; the laptop would show the manually configured IP, not 169.254.x.x.

D

A physical cable issue would prevent link, so the laptop would not even attempt DHCP and would not get an APIPA address.

1228
MCQhard

A network engineer notices that Host A in VLAN 10 (10.10.10.50/24) can successfully ping its default gateway 10.10.10.1, but cannot ping the VLAN 20 SVI (10.20.20.1) or any hosts in VLAN 20. The SVIs for both VLAN 10 and VLAN 20 are in an up/up state, and the switch's trunk ports are correctly allowing both VLANs. What is the most likely cause?

A.The ip routing global configuration command is missing.
B.The VLAN 20 SVI is administratively shut down.
C.The trunk between the access switch and the Layer 3 switch is misconfigured as an access port.
D.The default gateway on Host A is configured incorrectly.
AnswerA

The 'ip routing' global configuration command is what enables IPv4 forwarding between VLANs on a multilayer switch. With SVIs created and IP addresses assigned, the switch can answer pings to those addresses for local subnet traffic, but it will not route packets between VLANs unless 'ip routing' is enabled. Since Host A can successfully ping 10.10.10.1 (its own SVI gateway) but fails to reach Host B on VLAN 20, the missing command precisely explains the failure: the switch is essentially acting as a host on each VLAN rather than a router.

Why this answer

Host A can reach its default gateway (10.10.10.1), which is the VLAN 10 SVI, but cannot reach the VLAN 20 SVI (10.20.20.1) or any hosts in VLAN 20. This indicates that Layer 2 connectivity is working (trunk allows both VLANs, SVIs are up/up), but inter-VLAN routing is failing. On a multilayer switch, inter-VLAN routing requires the global command 'ip routing' to enable the switch's IP routing engine; without it, the switch acts as a Layer 2 device only and cannot forward packets between different VLANs.

Exam trap

Cisco often tests the distinction between a switch operating as a Layer 2 device versus a Layer 3 device, and the trap here is that candidates assume SVIs in an up/up state automatically provide inter-VLAN routing, forgetting the mandatory 'ip routing' command.

Why the other options are wrong

B

Candidates may overlook the explicit mention that the SVIs are up/up, mistakenly thinking a shut SVI could be the problem.

C

Trunk misconfiguration is a common inter-VLAN issue, but the scenario explicitly says the trunks are working properly, making this answer invalid.

D

The successful ping to the default gateway proves the gateway is correct. Without 'ip routing', the switch can't forward packets from VLAN 10 to VLAN 20, but it can respond to local VLAN requests.

1229
Multi-Selectmedium

Which TWO statements correctly describe the causes or implications of CRC errors, runts, giants, or output errors as seen in the output of 'show interface' or 'show interface status'?

Select 2 answers
A.CRC errors are always caused by a faulty switch port and require port replacement.
B.A high number of runts on an interface typically indicates excessive collisions or a faulty NIC.
C.Giants are frames that exceed the maximum transmission unit (MTU) and are always discarded by the switch.
D.Output errors, including late collisions, can be caused by a duplex mismatch between the switch and the connected device.
E.The 'show controllers' command provides a detailed view of CRC errors but does not show runts or giants.
AnswersB, D

A runt is an Ethernet frame shorter than the 64-byte minimum, often generated when a collision aborts transmission or when a faulty NIC emits undersized frames. On a modern full-duplex link, collisions should not occur, so a persistent runt count usually points to a defective NIC, bad cabling, or a misconfigured interface. High runt counts can also indicate excessive network congestion in legacy half-duplex environments.

Why this answer

Runts—frames smaller than 64 bytes—often result from collisions truncating frames on half-duplex links or a faulty NIC. Option D is correct because duplex mismatch can cause late collisions, which appear as output errors in 'show interface'; a device on one side full-duplex and the other half-duplex leads to collisions and framing errors. Option A is wrong because CRC errors can stem from faulty cabling, interference, or a mismatched NIC, not exclusively a bad switch port.

Option C is wrong because giants (frames over maximum MTU) may be forwarded if the interface is configured with jumbo frames or the switch is set to accept oversize frames. Option E is wrong because 'show controllers' displays frame-size errors like runts and giants, including details beyond CRC errors.

Exam trap

Cisco often tests the misconception that CRC errors always indicate a bad port (trap A) and that giants are always discarded (trap C), when in reality both can have multiple causes and switches can be configured to forward larger frames.

Why the other options are wrong

A

This statement is too absolute; CRC errors often stem from Layer 1 issues like bad cables or noise, not always a defective port.

C

The statement is too definitive; giants can be forwarded if jumbo frame support is enabled.

E

This statement is incorrect because 'show controllers' often includes runt and giant counters on many Cisco platforms.

1230
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure Root Guard on a designated port, Loop Guard on a non-designated port, and BPDU Guard on a PortFast port, along with the recovery steps when a port enters err-disabled state.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps
Order
1Step 1
2Step 2
3Step 3
4Step 4

Why this order

The order follows the logical sequence: enter config mode, then configure each guard feature on its respective port, and finally set the errdisable recovery to automatically re-enable ports after a BPDU Guard violation.

Exam trap

The trap is that candidates may think the order of configuring the guards is arbitrary, but the question explicitly requires a specific sequence. Pay close attention to the order in which features are listed in the stem.

Why candidates pick the wrong answer

B

Candidates might pick this because they think BPDU Guard should be configured first since it's a common protection, or they may misremember the order.

C

Candidates might pick this because they think the order of guard configuration doesn't matter, but the question explicitly requires a specific order.

D

Candidates might pick this because they think BPDU Guard should be configured after Root Guard but before Loop Guard, or they may confuse the order.

1231
PBQhard

You are connected to R1. The network consists of R1, SW1, and two hosts (Host-A on VLAN 10, Host-B on VLAN 20). SW1 has two access ports (one per VLAN) and a trunk to R1. Configure R1 for router-on-a-stick inter-VLAN routing. The current configuration has a native VLAN mismatch and a missing subinterface for VLAN 20. Fix these issues so that Host-A and Host-B can ping each other.

Hints

  • Check if all required subinterfaces are present.
  • Examine the native VLAN on the trunk.
  • Verify that IP routing is enabled globally.
A.Configure interface G0/0.20 with encapsulation dot1Q 20 and IP address 192.168.20.1 255.255.255.0, set native VLAN to 1 on the trunk, and enable ip routing.
B.Configure interface G0/0.20 with encapsulation dot1Q 20 and IP address 192.168.20.1 255.255.255.0, set native VLAN to 99 on the trunk, and enable ip routing.
C.Configure interface G0/0.20 with encapsulation dot1Q 20 and IP address 192.168.20.1 255.255.255.0, set native VLAN to 1 on the trunk, but do not enable ip routing.
D.Configure interface G0/0.20 with encapsulation dot1Q 20 and IP address 192.168.20.1 255.255.255.0, set native VLAN to 99 on the trunk, and do not enable ip routing.
AnswerA
solution
! R1
configure terminal
interface GigabitEthernet0/0.20
encapsulation dot1Q 20
ip address 192.168.20.1 255.255.255.0
exit
interface GigabitEthernet0/0
no encapsulation dot1Q 99
exit
ip routing
end

Why this answer

The native VLAN mismatch exists: R1 expects native VLAN 99, but SW1 likely uses native VLAN 1 (default). This causes CDP/STP issues but not directly inter-VLAN routing; however, for proper operation, set native VLAN to 1 on R1. Additionally, the subinterface for VLAN 20 is missing, so traffic from VLAN 20 cannot be routed.

Finally, 'ip routing' is disabled, preventing any inter-VLAN routing. Solution: change native VLAN on trunk to 1, create subinterface G0/0.20 with encapsulation dot1Q 20 and IP 192.168.20.1/24, and enable ip routing.

Exam trap

Be careful to identify all issues in the scenario. Candidates often focus only on the missing subinterface and forget to check the native VLAN mismatch and the global 'ip routing' command. Always verify that routing is enabled and that native VLANs match on both ends of the trunk.

Why the other options are wrong

B

The native VLAN mismatch is not resolved; the switch likely uses native VLAN 1, so R1 should also use 1 or both sides must be configured consistently.

C

IP routing is disabled by default on Cisco routers; it must be explicitly enabled for the router to perform routing functions.

D

Two errors: native VLAN mismatch persists and IP routing is disabled, so packets cannot be routed between VLANs.

Why candidates pick the wrong answer

B

Candidates may think that setting native VLAN to 99 is correct because it was mentioned in the scenario, but they overlook that the switch uses default native VLAN 1.

C

Candidates may assume that creating subinterfaces automatically enables routing, or they may forget that 'ip routing' is a global command required for inter-VLAN routing.

D

Candidates may think that only the missing subinterface needs to be created, ignoring the other two issues, or they may confuse native VLAN configuration.

1232
PBQhard

You are connected to R1. Configure IPv4 and IPv6 addressing on R1's interfaces and verify reachability to R2. The current configuration has a wrong subnet mask on G0/0, missing default gateway for IPv4, and R1's IPv6 address is configured using EUI-64 while R2 uses a static IPv6 address. Fix these issues so that R1 can ping both R2's IPv4 and IPv6 addresses.

Network Topology
G0/0192.0.2.1/24G0/0192.0.2.2/30linkR1R2

Hints

  • Compare the subnet masks on R1 and R2's G0/0 interfaces.
  • Check the IPv4 default route — the next-hop must be reachable.
  • R1's IPv6 EUI-64 will not match the static address on R2; use a static assignment on the same subnet.
A.Change R1 G0/0 subnet mask to /30, add a default route via 192.0.2.2, and configure a static IPv6 address 2001:db8:1::1/64 on G0/0.
B.Change R1 G0/0 subnet mask to /30, add a default route via 192.0.2.254, and keep the EUI-64 IPv6 address on G0/0.
C.Change R1 G0/0 subnet mask to /24, add a default route via 192.0.2.2, and configure a static IPv6 address 2001:db8:1::1/64 on G0/0.
D.Change R1 G0/0 subnet mask to /30, add a default route via 192.0.2.2, and keep the EUI-64 IPv6 address on G0/0.
AnswerA
solution
! R1
enable
configure terminal
interface GigabitEthernet0/0
ip address 192.0.2.1 255.255.255.252
no ipv6 address 2001:db8:1::/64 eui-64
ipv6 address 2001:db8:1::1/64
exit
no ip route 0.0.0.0 0.0.0.0 192.0.2.254
ip route 0.0.0.0 0.0.0.0 192.0.2.2
end
write memory

Why this answer

The problem had three issues: (1) R1's G0/0 subnet mask was /24 (255.255.255.0) but R2's G0/0 was /30 (255.255.255.252), causing an IP subnet mismatch. (2) R1 lacked a default gateway for IPv4; the static route pointed to 192.0.2.254 which is not reachable. (3) R1's IPv6 EUI-64 configuration on G0/0 generates an interface ID from the MAC, but R2 expects a static address 2001:db8:1::2/64, so R1 must use a static IPv6 address on the same subnet. The fix: change R1's G0/0 mask to /30, add a default route via R2's G0/0 IP (192.0.2.2), and configure a static IPv6 address (e.g., 2001:db8:1::1/64) on R1's G0/0.

Exam trap

Be careful not to confuse the default gateway with an arbitrary IP; it must be the next-hop router's interface IP on the same subnet. Also, remember that EUI-64 generates a unique interface ID from the MAC, which may not match a statically configured peer address—both sides must use consistent addressing methods.

Why the other options are wrong

B

The default gateway must be R2's directly connected interface IP (192.0.2.2), not 192.0.2.254. EUI-64 cannot be used if the peer expects a specific static address on the same subnet.

C

The subnet mask must be consistent on both ends of the link. A /24 mask on one side and /30 on the other creates overlapping subnets and routing issues.

D

EUI-64 does not guarantee that the resulting IPv6 address will be on the same subnet as a statically configured peer address. For direct connectivity, both routers must have addresses in the same subnet.

Why candidates pick the wrong answer

B

Candidates may think the original default route (192.0.2.254) is correct or that EUI-64 is always acceptable for IPv6 connectivity.

C

Candidates might think the mask only needs to be consistent within the same network or that a /24 is a common default mask, overlooking the specific /30 used by R2.

D

Candidates may assume EUI-64 is always compatible or that IPv6 neighbor discovery will automatically resolve the mismatch.

1233
MCQmedium

A controller API returns this data: { "device": { "hostname": "Dist-1", "interfaces": [ {"name": "Gig0/0", "status": "up"}, {"name": "Gig0/1", "status": "down"} ] } } Which statement is correct?

A.The response is XML because it contains nested elements
B.The interfaces field is an array of objects
C.The hostname field is a list
D.The format shown is YAML
AnswerB

Correct. This is correct. The interfaces field is enclosed in square brackets, which in JSON means an array. Each item inside the array is an object containing keys such as name and status.

Why this answer

The interfaces field is an array of objects. The giveaway is the square brackets around the interface entries. In JSON, square brackets represent an array, and braces represent an object.

Each interface entry inside that array has key-value pairs such as name and status, which makes each entry its own object. In plain language, the controller is returning a list of interface records for one device. The hostname field, by contrast, is a single value.

This style of question appears in automation topics because the exam wants you to recognize common data structures used in controller APIs without requiring deep programming expertise. Understanding the difference between an object and an array is usually enough.

Exam trap

Be careful not to confuse JSON arrays with objects or strings. Pay attention to the brackets and braces used.

Why the other options are wrong

A

This option is wrong because the response is in JSON format, not XML. JSON uses curly braces and key-value pairs, while XML uses tags to define elements.

C

The hostname field is a string, not a list, as it contains a single value ('Dist-1') and does not represent multiple items or entries.

D

This option is wrong because the format shown in the response is JSON, not YAML. YAML uses indentation and a different syntax for data representation, which is not present here.

When would these options actually be correct?

A

If the question was framed to ask about a data format that includes nested elements and is specifically about XML, then this option could be correct. For example, a question asking about the structure of an XML response with nested tags would make this statement valid.

C

If the question were to present a JSON object where the hostname field contained multiple values, such as 'hostname': ['Dist-1', 'Dist-2'], then the statement would be correct, as it would indeed be a list of hostnames.

D

If a question asked about a configuration file or data representation that explicitly used YAML syntax, such as a document with key-value pairs and indentation, then this option would be correct.

Why candidates pick the wrong answer

A

Candidates may confuse JSON's nested structure with XML's hierarchical format, leading them to mistakenly identify JSON as XML due to the presence of nested elements.

C

Candidates might confuse the term 'field' with the concept of a list, mistakenly thinking that any collection of data, even a single string, qualifies as a list.

D

Candidates may confuse JSON with YAML due to their similar use cases in data serialization, leading them to mistakenly identify the format based on the presence of nested structures.

1234
Multi-Selecteasy

A developer is interacting with a REST API exposed by a network controller. Which two statements correctly describe common REST behavior?

Select 2 answers
A.GET is commonly used to retrieve resource data
B.POST always replaces an existing resource completely
C.JSON is a common data format used in REST APIs
D.REST requires SNMP as the transport mechanism
AnswersA, C

GET is an HTTP method defined as a safe, idempotent read operation in REST. It retrieves a representation of a resource identified by a URI, and should not alter server state. In network controller APIs, GET is used to fetch configuration, status, or telemetry data without side effects.

Why this answer

REST APIs commonly use HTTP methods such as GET, POST, PUT, and DELETE, and JSON is one of the most common payload formats.

Exam trap

A common exam trap is assuming that POST always replaces an existing resource completely, which is incorrect. In REST API design, POST is typically used to create new resources or trigger server-side processing, whereas PUT is the method that fully replaces an existing resource. Confusing these two can lead to incorrect assumptions about how network controllers handle configuration changes or data updates.

This misunderstanding may cause candidates to select POST as the answer for resource replacement questions, which is a frequent mistake in Cisco automation and programmability topics.

Why the other options are wrong

B

Option B is incorrect because POST does not always replace an existing resource completely; it usually creates new resources or triggers processing. PUT is the method associated with full resource replacement.

D

Option D is incorrect because REST APIs do not require SNMP as the transport mechanism; they typically use HTTP or HTTPS protocols for communication.

When would these options actually be correct?

B

If the question asked 'Which HTTP method is used to replace an existing resource completely?' then POST could be correct in some APIs that use POST for update operations, though PUT is more standard.

D

In a question asking about network management protocols, SNMP would be correct if the scenario involves monitoring or managing network devices using SNMP, such as polling interface statistics or receiving traps from routers.

Why candidates pick the wrong answer

B

Candidates may confuse POST with PUT, thinking POST can fully replace a resource, or they may have experience with APIs that misuse POST for updates.

D

Candidates may confuse REST with network management protocols like SNMP, or think that REST APIs for network controllers must use SNMP because of the network context.

1235
MCQhard

A router interface is configured with the prefix 2001:db8:acad:12::/64 and uses EUI-64 to build the interface ID. What is the main purpose of EUI-64 in this context?

A.It automatically creates the interface ID portion of the IPv6 address from the MAC address.
B.It changes the /64 prefix into a /48 prefix for summarization.
C.It replaces the need for a link-local address.
D.It encrypts IPv6 traffic between neighbors.
AnswerA

EUI-64 is the interface ID generation method used when a router interface has no explicit 64-bit host portion configured. The 48-bit MAC address is split, the hex value FFFE is inserted between the OUI and the serial number, and the universal/local bit is flipped to form the 64-bit interface identifier. This automatically completes the IPv6 address and is why the statement is correct.

Why this answer

EUI-64 is used to automatically generate the interface identifier portion of the IPv6 address from the underlying MAC address. In practical terms, the /64 prefix provides the network portion, and EUI-64 helps derive the lower 64 bits without the administrator manually typing a full host portion. This can make addressing easier in environments where automatic formation is desired.

The important idea is that EUI-64 affects the interface ID, not the prefix length or the routing behavior of the network. It is an address-construction method, not a routing protocol.

Exam trap

Remember, EUI-64 is about address generation, not routing or network configuration. Focus on its role in forming the interface ID.

Why the other options are wrong

B

This option is incorrect because EUI-64 does not change the prefix length of an IPv6 address; it is used solely for generating the interface ID from a MAC address within the existing prefix.

C

This option is incorrect because EUI-64 does not replace the need for a link-local address; link-local addresses are essential for local network communication in IPv6, regardless of how the global address is generated.

D

This option is wrong because EUI-64 does not encrypt IPv6 traffic; it is used to generate the interface ID from the MAC address, which is unrelated to encryption processes.

When would these options actually be correct?

B

In a different question, if it asked about IPv6 address summarization techniques, and it provided a scenario where a network administrator needs to summarize multiple /64 prefixes into a single /48 prefix for routing efficiency, then this option would be correct.

C

In a different question setup, if the question asked about a technology that eliminates the need for link-local addresses in specific scenarios, such as a proprietary protocol that uses a different addressing scheme, then this option could be correct.

D

In a different question that asks about the security features of IPv6 protocols, if it specifically inquires about methods to secure communications between neighboring devices, then the option could be correct if discussing encryption mechanisms like IPsec, which can be used in conjunction with IPv6.

Why candidates pick the wrong answer

B

Candidates may choose this option due to confusion about IPv6 prefix lengths and summarization concepts, leading them to incorrectly associate EUI-64 with prefix manipulation instead of its actual function in interface ID generation.

C

Candidates may choose this option due to a misunderstanding of IPv6 addressing concepts, believing that EUI-64's role in generating global addresses might also extend to eliminating the necessity for link-local addresses.

D

Candidates may choose this option due to a misunderstanding of IPv6 security features, confusing the role of EUI-64 with the need for secure communication methods, leading them to associate it with encryption.

1236
PBQhard

You are connected to R1 via console. R1 and R2 are connected via two serial links: Serial0/0/0 (10.0.0.1/30) and Serial0/0/1 (10.0.0.5/30). OSPF is configured on both links. However, the OSPF neighbor adjacency is stuck in EXSTART/EXCHANGE state. You suspect a mismatch in OSPF parameters. You need to identify and fix the issue.

Network Topology
S0/0/010.0.0.1/30S0/0/010.0.0.2/30R1R2

Hints

  • EXSTART/EXCHANGE state indicates a problem with the Database Descriptor (DBD) packet exchange.
  • Check the MTU on the interfaces; a mismatch can cause this issue.
  • Use show ip interface to verify the MTU value.
A.Check and adjust the MTU on the serial interfaces to match.
B.Check and adjust the OSPF hello and dead timers to match.
C.Check and adjust the OSPF network type on the interfaces to match.
D.Check and adjust the OSPF area ID on the interfaces to match.
AnswerA
solution
! R1
interface Serial0/0/0
ip mtu 1400

! R2
interface Serial0/0/0
ip mtu 1400

Why this answer

The adjacency stuck in EXSTART/EXCHANGE is often due to an MTU mismatch. If one interface has a lower MTU, the DBD packets may be fragmented or rejected, preventing the exchange of LSAs. Setting the same MTU on both sides resolves the issue.

Exam trap

Do not confuse the symptoms of MTU mismatch with other OSPF parameter mismatches. MTU mismatch specifically causes problems in EXSTART/EXCHANGE, while timer mismatches cause issues in INIT/2-WAY, and area ID mismatches prevent adjacency entirely.

Why the other options are wrong

B

The specific factual error is that timer mismatches affect the neighbor discovery phase, not the database exchange phase.

C

The specific factual error is that network type affects the election of DR/BDR and adjacency formation, but not the DBD exchange process.

D

The specific factual error is that area ID mismatches cause OSPF to ignore hello packets, so the adjacency never progresses beyond DOWN.

Why candidates pick the wrong answer

B

Candidates often confuse the symptoms of timer mismatches with MTU mismatches, as both involve OSPF neighbor issues.

C

Candidates may think that network type affects all stages of OSPF adjacency, but it primarily impacts the earlier stages.

D

Candidates may think area ID mismatches could cause issues later in the adjacency process, but they actually prevent any neighbor relationship.

1237
MCQhard

A host address is 10.77.4.141/28. Which address is the network address of the subnet?

A.10.77.4.128
B.10.77.4.143
C.10.77.4.144
D.10.77.4.112
AnswerA

The host address 10.77.4.141 falls within the /28 subnet that starts at 10.77.4.128, because the /28 block size is 16 addresses (128-143). The network address is the first address of that block, where all host bits are zero, so 10.77.4.128 is the correct network address. Any address in the range 10.77.4.129 through 10.77.4.142 is valid for hosts, while .143 is the broadcast.

Why this answer

A /28 subnet has a block size of 16. In practical terms, the last-octet blocks are 0-15, 16-31, 32-47, and so on. Because 141 falls within the 128-143 block, the network address is 10.77.4.128.

This is a clean addressing-boundary question that rewards careful block calculation rather than guesswork.

Exam trap

Be careful not to confuse host addresses with network addresses. Always calculate the subnet block to find the network address.

Why the other options are wrong

B

Option B, 10.77.4.143, is incorrect because it falls within the usable host range of the subnet defined by 10.77.4.128/28, which spans from 10.77.4.129 to 10.77.4.142. The network address must always be the first address in the subnet.

C

This option is wrong because 10.77.4.144 is not the network address for the subnet defined by 10.77.4.141/28; the correct network address is 10.77.4.128, which is the first address in the subnet range.

D

Option D, 10.77.4.112, is incorrect because it does not fall within the subnet defined by the CIDR notation /28, which covers addresses from 10.77.4.128 to 10.77.4.143. The network address for this subnet is 10.77.4.128.

When would these options actually be correct?

B

In a different question where the task is to identify the last usable host address in the subnet, 10.77.4.143 would be correct, as it is the highest address before the broadcast address of 10.77.4.143 in a /28 subnet.

C

If the question asked for the first usable host address in the subnet instead of the network address, then 10.77.4.144 could be considered correct, as it is the first address after the network address (10.77.4.128) and before the broadcast address (10.77.4.143).

D

In a different question where the subnet mask was /24 and the host address was 10.77.4.112/24, option D would be the correct answer as it would represent the network address for that subnet, which spans from 10.77.4.0 to 10.77.4.255.

Why candidates pick the wrong answer

B

Candidates may choose this option because it is close to the network address and may confuse it with a valid host address, especially if they misinterpret the subnetting boundaries.

C

Candidates may choose this option due to confusion between the network address and the first usable host address, especially if they misinterpret the subnetting concept or overlook the specifics of address allocation.

D

Candidates might choose option D due to a misunderstanding of subnetting, confusing the range of usable addresses with the network address, especially if they miscalculate the subnet boundaries.

1238
MCQhard

A network engineer is troubleshooting an OSPFv3 adjacency issue between two directly connected routers. Both routers are configured for OSPFv3 in area 0 on their GigabitEthernet0/0 interfaces. The engineer checks the OSPFv3 neighbor status on R1 and sees that the neighbor state is stuck in EXSTART. The engineer verifies that both interfaces are up and have IPv6 link-local addresses. What is the most likely cause of this problem?

A.Configure a global unicast IPv6 address on the interface.
B.Ensure that the MTU is the same on both sides of the link.
C.Change the router ID to be the same on both routers.
D.Change the network type to point-to-point.
AnswerB

An MTU mismatch prevents OSPFv3 from completing the DBD packet exchange, leaving the neighbor state stuck in EXSTART. During this phase, routers send Database Description packets that must fit within the interface MTU; if one side's MTU is lower, the packets are dropped, and the routers keep retransmitting without progressing to EXCHANGE. Aligning the MTU on both ends allows the DBD exchange to complete, moving the adjacency to FULL.

Why this answer

The EXSTART state in OSPF indicates that the routers have formed a bidirectional communication and are negotiating the master/slave relationship and the initial Database Description (DBD) packet exchange. A common cause for getting stuck in EXSTART is an MTU mismatch between the two interfaces, which prevents the DBD packets from being accepted by the neighbor, causing the process to stall.

Exam trap

Cisco often tests the MTU mismatch as a specific cause for OSPF adjacency being stuck in EXSTART, and candidates may mistakenly focus on router IDs or addressing instead of the packet size negotiation.

Why the other options are wrong

A

The problem is not due to missing global addresses; the adjacency is stuck at EXSTART, not at DOWN or INIT.

C

The show output shows different router IDs (192.168.1.1 and 192.168.1.2), so this is not the issue.

D

The adjacency is stuck in EXSTART, which is not typically resolved by changing network type; the issue is related to packet exchange.

1239
Drag & Dropmedium

Drag and drop the following steps into the correct order to troubleshoot an end-to-end connectivity issue using a bottom-up approach.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps
Order
1Step 1
2Step 2
3Step 3
4Step 4

Why this order

The correct troubleshooting order follows the OSI model bottom-up: start with physical connectivity (A), then verify Layer 3 addressing (B), use diagnostic tools (C) to isolate the failure, and finally implement the solution and verify restoration (D). Skipping layers can lead to misdiagnosis.

Exam trap

A common mistake is to begin with tools like ping before confirming physical and IP configuration; always validate lower layers first.

1240
MCQhard

A network engineer notices that after removing a standard ACL that was applied inbound on the internet-facing interface, the router is now receiving IP packets from the internet with source IP addresses in the 10.0.0.0/8 range, which were previously blocked. What is the most likely cause?

A.The original standard ACL only had a permit statement, so after removal the permit still takes effect because the ACL remains in the running configuration.
B.The ip access-group command on the interface remains but is missing the referenced ACL, causing the router to default to denying all ingress traffic except the previously permitted 10.0.0.0/8.
C.Removing the ACL from the interface eliminates the implicit deny at the end and restores the default permit all behavior, allowing all incoming traffic.
D.The ACL was reapplied in the outbound direction instead of inbound, so it now blocks traffic leaving the interface but not entering it.
AnswerC

Before removal, the applied ACL permitted only 10.0.0.0/8 and denied everything else (implicit deny all), which correctly blocked spoofed RFC 1918 traffic. Once the ACL is de-applied, the interface has no access list, so all traffic is permitted, including the previously blocked spoofed packets.

Why this answer

When a standard ACL is removed from an interface using the 'no ip access-group' command, the implicit deny any at the end of the ACL is also removed. By default, Cisco routers permit all IP traffic on an interface unless an ACL is applied to filter it. Therefore, after removal, the router reverts to its default permit-all behavior, allowing previously blocked traffic like source IPs in the 10.0.0.0/8 range.

Exam trap

Cisco often tests the misconception that removing an ACL from an interface leaves some filtering in place, when in fact it restores the default permit-all behavior, and candidates may confuse the implicit deny of an ACL with the default interface behavior.

Why the other options are wrong

A

Candidates may think that the ACL itself, if still configured, continues to filter traffic even when not applied to an interface.

B

A common misunderstanding is that the access-group line can persist without a valid ACL and cause some default behavior; in fact the entire command is removed.

D

Some candidates may confuse direction changes with removal and assume the ACL is still filtering traffic in some way, but the symptom clearly indicates no filtering at all.

1241
MCQhard

A packet is destined for 192.168.40.130. The routing table contains 192.168.40.0/24, 192.168.40.128/25, and 0.0.0.0/0. Which route is used?

A.192.168.40.0/24
B.192.168.40.128/25
C.0.0.0.0/0
D.No route can be used because the entries overlap
AnswerB

This is correct because 192.168.40.130 falls within that more specific range.

Why this answer

The /25 route is used because it is the most specific matching prefix. In plain language, even though the /24 and the default route also technically match, the router prefers the entry that most precisely describes the destination range. Since 192.168.40.130 falls inside 192.168.40.128/25, that route wins under longest-prefix match.

This is a classic routing-table interpretation pattern. The router does not start with the default route when more specific routes exist, and it does not choose the /24 simply because it is familiar. Specificity comes first.

Exam trap

A common exam trap is assuming that the default route or a larger subnet like /24 will be chosen over a more specific subnet like /25. Candidates may incorrectly think the default route is preferred or that overlapping routes cause ambiguity. However, routers always use the longest prefix match rule, which means the route with the most specific subnet mask that includes the destination IP is selected.

Misunderstanding subnet mask lengths or ignoring longest prefix match leads to wrong answers in routing questions.

Why the other options are wrong

A

192.168.40.0/24 is a valid route but less specific than 192.168.40.128/25. Since the destination IP falls within both, the router prefers the more specific /25 route, so this option is incorrect.

C

0.0.0.0/0 is the default route and only used when no other route matches. Since more specific routes exist for the destination IP, this option is incorrect.

D

Overlapping routes like /24 and /25 are common and resolved by longest prefix match. The presence of overlapping entries does not prevent route selection, so this option is incorrect.

When would these options actually be correct?

A

This option would be correct if the question specified that the destination IP was 192.168.40.200, which does not fall within the 192.168.40.128/25 range, making the broader 192.168.40.0/24 the best match.

C

If the question stated that the routing table only contained the default route 0.0.0.0/0 and no other specific routes for the destination IP, then this option would be correct as it would be the only available route for the packet.

D

In a different question setup where the routing table contains overlapping routes and the question explicitly states that the router cannot resolve which route to use due to ambiguity, this option would be correct, indicating that no definitive route can be selected.

Why candidates pick the wrong answer

A

Candidates may choose this option because it represents a broader subnet that includes the destination IP, leading to a common misconception that broader routes are always preferred over more specific ones.

C

Candidates may choose this option due to the familiarity with the default route concept, mistakenly believing it serves all traffic when no specific routes are present, without considering the specific match of the destination IP.

D

Candidates may choose this option due to a misunderstanding of how overlapping routes are prioritized, mistakenly believing that overlaps inherently prevent routing rather than recognizing the specificity of the routes.

1242
MCQhard

Two OSPF routers connected over Ethernet fail to become neighbors. Their interfaces are up/up and in the same IPv4 subnet. One router uses area 0 and the other uses area 1 on the connecting interfaces. What is the most likely cause?

A.Mismatched OSPF process IDs
B.Mismatched OSPF areas on the shared link
C.Missing default routes
D.Different router IDs
AnswerB

OSPF neighbors must agree on the area ID configured on the link. If one router places the interface in area 0 and the other in area 1, Hello packets are rejected because the area ID field doesn't match, preventing neighbor state from advancing beyond INIT. This is a fundamental adjacency requirement, separate from process ID or router ID issues.

Why this answer

OSPF neighbors on the same link must agree on key parameters, including the area assigned to that interface. A mismatch prevents the adjacency from forming.

Exam trap

A common exam trap is assuming that OSPF process IDs must match between neighbors for adjacency to form. Many candidates mistakenly focus on process ID alignment, but OSPF process IDs are locally significant and do not need to match. The real cause of adjacency failure in this scenario is the mismatch in OSPF area IDs on the shared link.

This subtle difference often leads to confusion, causing candidates to overlook the critical role of area consistency in neighbor formation and select incorrect answers related to process IDs or router IDs.

Why the other options are wrong

A

Mismatched OSPF process IDs do not prevent neighbor formation because process IDs are locally significant identifiers on each router. They do not need to match for adjacency to form, so this option is incorrect.

C

Missing default routes do not affect OSPF neighbor formation. Default routes influence routing decisions but are not required for establishing OSPF adjacencies, so this option is incorrect.

D

Different router IDs are necessary for OSPF neighbors to uniquely identify each router. Having different router IDs does not cause adjacency failure, so this option is incorrect.

When would these options actually be correct?

A

In a scenario where two OSPF routers are configured with the same subnet but have different OSPF process IDs and are also in the same area, a question could ask why they are unable to establish a neighbor relationship. In this case, mismatched process IDs would be the correct answer.

C

In a scenario where two routers are configured to use OSPF but are unable to reach each other due to missing default routes, a question might ask about the impact of routing on OSPF neighbor formation. In this case, if the routers cannot route packets to each other, the absence of a default route could prevent them from becoming neighbors.

D

In a different question setup, if two OSPF routers were configured in the same area but had mismatched router IDs, the question could ask about issues in OSPF route selection or redundancy. In this case, the option would be correct if the question focused on how router IDs affect OSPF operations.

Why candidates pick the wrong answer

A

Candidates may mistakenly believe that OSPF process IDs are critical for establishing neighbor relationships, leading them to choose this option without fully considering the area configuration requirements.

C

Candidates may choose this option because they might confuse general routing issues with OSPF neighbor formation, thinking that routing paths are essential for neighbor relationships, leading to the assumption that missing default routes could be a factor.

D

Candidates may confuse router IDs with OSPF neighbor relationships, thinking that differing IDs indicate a fundamental misconfiguration. This misunderstanding can lead them to incorrectly select this option when they see OSPF-related issues.

1243
MCQhard

Exhibit: Hosts on the inside network can reach the internet, but inbound connections to a published web server fail. Static NAT is configured. What is the most likely missing piece?

A.A default route on the inside host
B.An ACL permit entry allowing TCP port 80 or 443 to the translated address
C.PAT overload on the outside interface
D.DHCP relay toward the web server
AnswerB

Static NAT creates the one-to-one mapping between the public IP and the web server's private IP, but packet filtering is applied independently of the translation. An inbound ACL on the outside interface must explicitly permit TCP ports 80/443 destined to the translated (public) address; without that permit, the router silently drops the HTTP/HTTPS packets even though the NAT entry exists. This permit entry is the missing piece that completes the inbound web access path.

Why this answer

Static NAT provides the address translation, but traffic still must be permitted by an inbound ACL or firewall policy on the outside interface. Option A is incorrect because a default route on the inside host affects outbound traffic, not inbound connections. Option C is wrong since PAT overload is for many-to-one translation and is not required here, and it would not block inbound traffic if static NAT is already configured.

Option D is incorrect because DHCP relay does not influence inbound access to a web server; it only forwards DHCP requests from clients to a remote DHCP server.

Exam trap

Many candidates assume that static NAT alone guarantees inbound access, forgetting that an inbound ACL on the outside interface must explicitly permit the traffic.

Why the other options are wrong

A

A default route on the inside host controls outbound traffic, not inbound connections from the internet.

C

PAT overload is used for many-to-one translation and would not block inbound traffic if static NAT is already configured.

D

DHCP relay forwards DHCP requests to a remote server and does not affect inbound HTTP/HTTPS access to a web server.

When would these options actually be correct?

A

In a scenario where the question specifies that hosts on the inside network cannot reach any external resources, and the configuration is missing a default route on the inside host, this option would be correct. For example, if the question stated that internal users cannot access the internet at all, then a default route would be necessary.

C

In a different scenario where multiple internal hosts need to share a single public IP address for outbound connections, a question might ask about the configuration needed to enable this. In that case, the correct answer could be PAT overload on the outside interface to allow multiple hosts to access the internet simultaneously.

D

In a different scenario where a web server is on a different subnet and requires DHCP for IP assignment, a question might ask about enabling communication between the server and clients. In this case, a DHCP relay would be necessary to forward DHCP requests from clients to the server's subnet.

Why candidates pick the wrong answer

A

Candidates may confuse the need for proper routing with the issue of inbound connections, leading them to believe that a default route is necessary for all types of connectivity, including inbound traffic.

C

Candidates may choose this option because they associate NAT configurations with address translation and might overlook the specific context of static NAT versus PAT, leading to confusion about their roles in inbound and outbound traffic.

D

Candidates may confuse DHCP relay with general network connectivity issues, mistakenly believing that it could help resolve inbound connection problems to a web server, especially if they have encountered similar scenarios in their studies.

1244
MCQhard

An administrator configures a GRE tunnel interface on a router with the following: interface Tunnel0, tunnel source GigabitEthernet0/0, tunnel destination 192.168.2.2. What is the main purpose of this configured tunnel?

A.It creates a logical tunnel across another network.
B.It enables PPP authentication on a serial interface.
C.It configures WPA3 security for a wireless bridge.
D.It enables BGP between autonomous systems automatically.
AnswerA

The configured tunnel interface takes the original packet and wraps it in a new IP header, with the tunnel source and destination addresses serving as the endpoints of that encapsulation. This creates a logical, virtual path that traverses an underlying physical or routed network, allowing traffic from two remote sites to appear as if they are directly connected even though they are separated by intermediate hops. Thus, the purpose is to establish an overlay network across another network, not to provide any security or link-level protocol function.

Why this answer

GRE is a tunneling mechanism used to carry one type of traffic over another network path by encapsulating packets. In practical terms, the configuration creates a logical tunnel between endpoints so traffic can cross an underlying IP network as if a virtual path existed between them. The key point is that GRE is about tunneling, not encryption by itself.

This distinction matters because people often assume tunnels automatically imply encryption. GRE by itself does not provide that.

Exam trap

A frequent exam trap is confusing GRE tunnels with encryption or automatic routing protocol establishment. Candidates often assume that because GRE creates a tunnel, it also encrypts traffic or automatically enables protocols like BGP. However, GRE only encapsulates packets and does not provide confidentiality or integrity.

Encryption requires pairing GRE with IPsec. Additionally, routing protocols must be explicitly configured over the tunnel interface; the tunnel itself does not initiate or enable them. Misreading the tunnel configuration as PPP authentication or wireless security is another common pitfall, as GRE operates at Layer 3 and is unrelated to those technologies.

Why the other options are wrong

B

Incorrect. PPP authentication applies to serial interfaces and point-to-point links, but the exhibit shows a GRE tunnel configuration, not PPP on a serial link.

C

Incorrect. WPA3 is a wireless security protocol unrelated to GRE tunnels, which operate at Layer 3 and do not configure wireless security settings.

D

Incorrect. GRE tunnels do not automatically enable BGP or any routing protocol; routing protocols must be explicitly configured over the tunnel interface.

When would these options actually be correct?

B

In a different question that asks about the configuration of a serial interface and its authentication methods, option B would be correct if the context involved enabling PPP authentication to secure data transmission over that interface.

C

This option would be correct in a question that asks about the security protocols used in a wireless network setup, specifically focusing on the implementation of WPA3 for securing a wireless bridge connection. For example, a question might ask, 'What security protocol is used to enhance the security of a wireless bridge?'

D

If the exam question specifically asked about the configuration of a network that uses BGP to connect multiple autonomous systems over a tunnel, then this option could be correct. For example, a question might describe a scenario where BGP is being used to facilitate communication between two ISPs over a GRE tunnel.

Why candidates pick the wrong answer

B

Candidates may be tempted by this option due to familiarity with PPP authentication in networking, leading them to mistakenly associate it with tunnel configurations without considering the specific context of the question.

C

Candidates may find this option tempting because they might confuse the concept of tunneling with securing wireless connections, especially if they have encountered both topics in their studies and are unsure of the specific context of the question.

D

Candidates might find this option tempting because BGP is commonly associated with network routing and can be involved in complex network setups, leading them to mistakenly connect it with tunnel configurations.

1245
PBQhard

You are connected to the console of R1. The network team wants to secure remote access. R1 currently has no SSH configuration. The domain name is 'example.com' and you need to generate an RSA key pair of 2048 bits and enable SSH version 2 on vty lines.

Network Topology
G0/010.0.0.1/24R1Management Network

Hints

  • SSH requires a domain name and RSA keys.
  • Use 'ip ssh version 2' to enforce SSHv2.
  • The vty lines must accept SSH only, not Telnet.
A.Configure IP domain name, generate RSA key pair with 2048 bits, set SSH version 2, and configure vty lines to use SSH.
B.Generate RSA key pair with 2048 bits, set SSH version 2, and configure vty lines to use SSH. Domain name is optional.
C.Configure IP domain name, generate RSA key pair with 2048 bits, and set SSH version 2. No need to configure vty lines.
D.Configure IP domain name, generate RSA key pair with 1024 bits, set SSH version 2, and configure vty lines to use SSH.
AnswerA
solution
! R1
ip domain-name example.com
crypto key generate rsa modulus 2048
ip ssh version 2
line vty 0 4
transport input ssh

Why this answer

SSH requires a hostname and domain name to generate RSA keys. Use 'ip domain-name example.com' then 'crypto key generate rsa general-keys modulus 2048' (the 'general-keys' keyword is required to avoid interactive prompts). Set SSH version 2 with 'ip ssh version 2' and restrict vty lines to SSH only with 'line vty 0 4' and 'transport input ssh'.

Answer A includes all required steps correctly. Option B misses the domain name. Option C omits vty line configuration.

Option D uses the wrong key size.

Exam trap

A common mistake is using 'crypto key generate rsa modulus 2048' without 'general-keys'; IOS requires the keyword to generate the key non-interactively.

Why the other options are wrong

B

The specific factual error: The domain name is mandatory for RSA key generation in SSH configuration.

C

The specific factual error: Vty lines require transport input ssh to allow SSH connections.

D

The specific factual error: The key size must be 2048 bits as specified; 1024 bits is insufficient.

Why candidates pick the wrong answer

B

Candidates pick this because they may think SSH can work without a domain name, but the RSA key generation command requires it.

C

Candidates pick this because they assume SSH is automatically enabled on vty lines after key generation, but it is not.

D

Candidates pick this because 1024 bits is a common default or older standard, but the question explicitly requires 2048 bits.

1246
MCQhard

A company wants an internal web server to be reachable consistently from the Internet using one known public IPv4 address. Which NAT approach best fits that requirement?

A.Static NAT
B.PAT overload
C.No NAT, because private IPv4 addresses are publicly routable
D.DHCP relay
AnswerA

This is correct because static NAT gives the server a permanent public mapping.

Why this answer

Static NAT is the best fit because it creates a fixed one-to-one relationship between the inside server and the public address. In practical terms, outside clients need a stable public identity for the server. They cannot rely on a translated address that changes session by session. Static NAT gives that predictability.

This is different from PAT, which is designed for many inside users sharing fewer public addresses for outbound traffic. The question is about publishing a server, not conserving addresses for client browsing. That is why static NAT is the strongest answer.

Exam trap

A frequent exam trap is selecting PAT overload as the solution for making an internal server reachable from the Internet. PAT is primarily designed for outbound traffic from multiple internal hosts sharing a single public IP, not for inbound access to a specific server. Another trap is thinking private IPv4 addresses are publicly routable, which they are not, so no NAT would fail to provide Internet reachability.

Also, confusing DHCP relay with NAT functions can mislead candidates, as DHCP relay only forwards DHCP messages and does not affect public IP mappings or server accessibility from the Internet.

Why the other options are wrong

B

PAT overload is incorrect because it is designed for many internal hosts sharing a single public IP for outbound traffic, not for providing a fixed public IP for inbound server access.

C

No NAT is incorrect since private IPv4 addresses are not routable on the public Internet; without NAT, the internal server cannot be reached from outside the private network.

D

DHCP relay is unrelated to NAT or public reachability; it only forwards DHCP requests across subnets and does not provide any public IP mapping for internal servers.

When would these options actually be correct?

B

If the question specified a scenario where multiple internal devices needed to access the Internet using a single public IP address without requiring consistent external access to a specific internal server, then PAT overload would be the correct choice.

C

In a scenario where the question states that the company has transitioned to using a new IPv6 addressing scheme that allows private addresses to be publicly routable, this option could be correct. The question might specify that the internal web server uses a public IPv6 address, eliminating the need for NAT.

D

If the question asked about the need to forward DHCP requests from clients on a different subnet to a DHCP server, then DHCP relay would be the correct answer. This scenario would involve configuring a network where clients cannot directly reach the DHCP server due to subnetting.

Why candidates pick the wrong answer

B

Candidates may choose this option because they understand that PAT allows for efficient use of IP addresses and might mistakenly believe it can also provide consistent access to a specific server.

C

Candidates may choose this option due to a misunderstanding of private and public IP address functionality, believing that private addresses can be used directly on the Internet without realizing the necessity of NAT for such configurations.

D

Candidates may confuse DHCP relay with NAT concepts, thinking that it relates to making services accessible over the Internet, leading them to select it based on a misunderstanding of its purpose in network configurations.

1247
MCQhard

A network engineer has configured an LACP EtherChannel between Switch1 and Switch2 by assigning interfaces to channel-group 1 with the mode passive on both switches. The engineer issues the show etherchannel summary command on Switch1 and sees the output below. The Port-channel interface remains down. Which action resolves the issue?

A.Configure the switchport mode as trunk on both sides.
B.Change the mode on one switch to active.
C.Verify that the native VLAN matches on both sides of the trunk.
D.Correct the speed and duplex settings on the member ports.
AnswerB

In LACP, passive mode interfaces only respond to received PDUs; they never initiate LACP negotiation. Since both switches are configured with passive mode, no LACP PDUs are exchanged, and the ports remain in a standalone (I) state. Changing one switch to active makes it actively send LACP PDUs, which prompts the passive peer to reply and complete the negotiation, allowing the member ports to bundle into the Port-channel. This directly fixes the root cause of the failure.

Why this answer

When both switches are configured with LACP mode passive, neither switch initiates the negotiation process because passive mode only responds to incoming LACP packets. By changing one side to active mode, that switch will actively send LACP packets, allowing the EtherChannel to form. The Port-channel interface remains down due to this negotiation failure, not because of VLAN or physical mismatch issues.

Exam trap

Cisco often tests the LACP mode interaction by setting both sides to passive, leading candidates to incorrectly focus on trunking, VLAN, or physical layer issues instead of recognizing that LACP requires at least one side to be active.

Why the other options are wrong

A

The show output indicates Layer 2 mode is already active, and trunking isn’t required for bundling. The issue is LACP protocol negotiation, not interface mode.

C

The Port-channel would still form even with a native VLAN mismatch; it would not be down (SD) and ports would not be stand-alone (I) solely because of VLAN mismatch.

D

The flags in the output (I, SD) are not consistent with a speed/duplex problem, and the explicit configuration of passive mode on both sides is the known root cause.

1248
MCQhard

Refer to the exhibit. A network engineer is investigating intermittent connectivity complaints on a gigabit uplink between two distribution switches. The engineer runs the show interfaces GigabitEthernet0/0 command on one of the switches. Based on the output, what is the most likely cause of the errors?

A.The interface is configured with an incorrect encapsulation type.
B.A damaged or faulty cable is causing excessive CRC errors.
C.A duplex mismatch exists between the connected devices.
D.The interface is assigned to the wrong VLAN.
AnswerB

The exhibit displays 5200 CRC errors (more than 5000) and 5231 input errors. High CRC counts directly indicate that received frames are being corrupted by physical layer issues such as a damaged cable, loose connector, or EMI on the copper segment.

Why this answer

The output shows a high number of CRC errors and runts, which typically indicate a Layer 1 physical-layer issue such as a damaged or faulty cable. CRC errors occur when frames fail the cyclic redundancy check due to signal degradation, noise, or physical damage to the cabling. On a gigabit uplink, this is the most likely cause of intermittent connectivity.

Exam trap

Cisco often tests the distinction between CRC errors (physical layer) and late collisions (duplex mismatch), so the trap here is that candidates see errors and assume a duplex mismatch without checking for the specific error types like late collisions or alignment errors.

Why the other options are wrong

A

Encapsulation problems cause protocol failures, not corrupted frames with CRC errors.

C

Candidates often mistake high CRC counts for duplex issues. The absence of collision-related counters rules out a duplex mismatch.

D

A wrong VLAN does not generate CRC errors on the physical interface.

1249
MCQhard

A PC connected to SW1 cannot reach the default gateway. The access port is assigned to VLAN 20, and the switch output shows that VLAN 20 is inactive. What is the most likely cause?

A.Port security has shut down the interface
B.VLAN 20 does not exist or is not active on the switch
C.The port must be converted to a trunk
D.The default gateway must be configured on the physical switch port
AnswerB

VLAN 20 must exist in the switch's VLAN database and be enabled (not shutdown) for the access port to forward frames. The exhibit's output indicates VLAN 20 is inactive, so the switch will not deliver the PC's frames to the default gateway in that VLAN. As a result, the PC cannot reach the gateway even if its IP address and gateway settings are correct.

Why this answer

The port is operationally up, but VLAN 20 is listed as inactive because that VLAN does not exist in the VLAN database. An access port assigned to a missing VLAN will not carry normal user traffic for that VLAN.

Exam trap

Ensure the VLAN is created and active in the VLAN database when troubleshooting connectivity issues.

Why the other options are wrong

A

This option is wrong because the question specifies that the PC cannot reach the default gateway due to VLAN issues, not because of port security settings. Port security would typically result in the interface being in an error-disabled state, which is not indicated here.

C

This option is incorrect because converting the port to a trunk would not resolve the issue of the PC not reaching the default gateway if VLAN 20 is not configured or active. The problem lies in the VLAN configuration, not the port type.

D

This option is incorrect because the default gateway is typically configured on the device (e.g., a router or PC) rather than on the switch port itself. The issue in the question pertains to VLAN configuration, not gateway settings.

When would these options actually be correct?

A

In a different scenario where a question describes a switch interface that has been configured with port security and is now in an error-disabled state due to exceeding the maximum allowed MAC addresses, this option would be correct. The question would need to focus on port security violations impacting connectivity.

C

In a different scenario, if the question stated that a device needs to communicate across multiple VLANs and the access port is incorrectly configured as a trunk, then converting it to a trunk would be necessary for proper communication. This would imply that the device needs to send and receive traffic from multiple VLANs.

D

In a scenario where a question states that a switch port is not forwarding traffic due to a misconfigured VLAN and also mentions that the default gateway is set incorrectly on the switch, this option could be correct. For example, if the switch is expected to route traffic for multiple VLANs and the gateway is misconfigured on the switch instead of the device.

Why candidates pick the wrong answer

A

Candidates may choose this option because they recognize port security as a common cause of connectivity issues on switches, leading them to associate it with the inability to reach a default gateway without fully analyzing the VLAN context provided in the question.

C

Candidates may choose this option because they associate VLAN communication issues with trunking, believing that a trunk configuration is universally required for VLAN traffic, leading to a misunderstanding of access port functionality.

D

Candidates may choose this option due to a misunderstanding of where default gateway settings are applied, thinking that the switch port must have a gateway configured for VLAN traffic to flow correctly.

1250
PBQmedium

You are connected to SW1, a Layer 2 switch. Port G0/1 connects to a PC in VLAN 10. Management requires that only one MAC address is allowed on this port, and if a violation occurs, the port should shut down and a log message should be generated. Additionally, you need to ensure that the port enables rapidly and does not wait for STP convergence. Currently, the PC has MAC address aaaa.bbbb.cccc.

Network Topology
G0/1SW1PC

Hints

  • Port security must be enabled first.
  • Use the 'mac-address' command to specify the allowed MAC.
  • PortFast bypasses STP listening/learning for access ports.
A.switchport port-security; switchport port-security maximum 1; switchport port-security mac-address aaaa.bbbb.cccc; switchport port-security violation shutdown; spanning-tree portfast
B.switchport port-security maximum 1; switchport port-security mac-address aaaa.bbbb.cccc; switchport port-security violation restrict; spanning-tree portfast
C.switchport port-security maximum 1; switchport port-security mac-address aaaa.bbbb.cccc; switchport port-security violation protect; spanning-tree portfast
D.switchport port-security maximum 1; switchport port-security mac-address aaaa.bbbb.cccc; switchport port-security violation shutdown; no spanning-tree portfast
AnswerA
solution
! SW1
interface GigabitEthernet0/1
switchport port-security
switchport port-security maximum 1
switchport port-security mac-address aaaa.bbbb.cccc
switchport port-security violation shutdown
spanning-tree portfast

Why this answer

Port security limits access to a port based on MAC addresses. The correct sequence must first enable port security with the `switchport port-security` command. Then setting maximum to 1 with a specific MAC ensures only that device can connect.

Violation shutdown disables the port if an unauthorized MAC appears. PortFast allows the port to transition to forwarding immediately, which is appropriate for end-user devices. Options B and C use wrong violation modes (restrict or protect) that do not shut the port and may not log.

Option D uses correct violation mode but omits PortFast, causing STP delays.

Exam trap

The key trap is confusing the three port security violation modes: shutdown (disables port + logs), restrict (drops traffic + logs but port stays up), and protect (drops traffic silently, no log). Also, remember that PortFast is needed for immediate forwarding on access ports.

Why the other options are wrong

B

The specific factual error: 'restrict' does not disable the port; it only filters traffic and logs the violation, but the port remains operational.

C

The specific factual error: 'protect' silently drops unauthorized traffic without logging or disabling the port.

D

The specific factual error: PortFast is required to bypass STP convergence; without it, the port will wait for STP to transition, causing delay.

Why candidates pick the wrong answer

B

Candidates might confuse 'restrict' with 'shutdown' because both generate log messages, but only 'shutdown' physically disables the port.

C

Candidates might think 'protect' is a stronger security mode, but it lacks logging and shutdown, which are explicitly required.

D

Candidates might think STP is always necessary for loop prevention, but on an access port with a single device, PortFast is safe and required for fast convergence.

1251
Multi-Selectmedium

A network operations team wants centralized logging from routers and switches and also wants meaningful severity filtering. Which two statements about syslog are correct?

Select 2 answers
A.Devices can send log messages to a remote syslog server for central storage
B.Severity levels allow filtering based on how serious an event is
C.Syslog is used to assign IP addresses dynamically to endpoints
D.Syslog entries replace SNMP counters for interface statistics
AnswersA, B

Syslog uses UDP port 514 by default to stream event messages from network devices to a centralized server, enabling aggregation, correlation, and long-term retention across the entire infrastructure. Local logging buffers are volatile and size-limited, so remote storage is critical for troubleshooting, compliance, and forensic analysis after a failure or security incident.

Why this answer

Syslog provides centralized event reporting by allowing devices to send log messages to a remote server (option A is correct). Severity levels enable filtering based on event seriousness (option B is correct). Option C is incorrect because syslog does not assign IP addresses dynamically—that is the role of DHCP.

Option D is incorrect because syslog logs events and does not replace SNMP counters, which remain the primary method for collecting interface statistics.

Exam trap

Be careful not to confuse syslog's use of UDP with TCP, and remember that syslog can send to multiple servers.

Why the other options are wrong

C

Syslog is not used for IP address assignment; that function is performed by DHCP.

D

Syslog does not replace SNMP counters for interface statistics; SNMP remains the primary method for collecting such data.

When would these options actually be correct?

C

In a question asking about protocols that assign IP addresses dynamically to endpoints, such as 'Which protocol assigns IP addresses automatically to devices on a network?', 'Syslog' would be incorrect, but if the question were about logging, this option would not apply. However, for a scenario where the question is about centralized logging, this option is never correct.

D

In a question asking 'Which protocol can be used to collect interface error counters from network devices?', SNMP would be correct, not syslog. Alternatively, if the question asked 'Which logging method can send event notifications to a central server?', syslog would be correct.

Why candidates pick the wrong answer

C

Candidates may confuse syslog with DHCP because both involve network services and the term 'log' might be misassociated with 'login' or 'assignment' processes.

D

Candidates may confuse syslog with SNMP because both are used for network monitoring and can provide information about device status, leading to the mistaken belief that syslog can replace SNMP counters.

1252
Multi-Selectmedium

Which TWO statements accurately describe how AI/ML concepts are applied to network operations in modern enterprise networks?

Select 2 answers
A.Supervised machine learning models can be used to classify network traffic into predefined categories, such as identifying whether traffic is voice, video, or data.
B.Anomaly detection algorithms, often based on unsupervised learning, can identify unusual network behavior that may indicate a security threat or device malfunction.
C.Reinforcement learning is primarily used to automatically classify email traffic as spam or not spam based on a labeled dataset.
D.Clustering algorithms, a type of unsupervised learning, are used to predict the exact bandwidth usage of a specific application over the next hour.
E.Predictive analytics in network operations relies solely on static thresholds defined by network administrators to forecast potential failures.
AnswersA, B

Supervised machine learning models such as decision trees, support vector machines, or neural networks are trained on labeled traffic datasets, where each flow is tagged as voice, video, or data. Once trained, the model extracts features like packet length, protocol, port numbers, and inter-arrival times to accurately classify unseen traffic. This classification directly supports network policies, enabling differentiated QoS marking, access control, or security inspection, and improves with more representative training data.

Why this answer

Supervised learning uses labeled data to classify traffic (e.g., voice, video, data). Option B is correct because anomaly detection often uses unsupervised learning to identify deviations from normal behavior. Option C is wrong because reinforcement learning is not used for spam classification; that task uses supervised learning.

Option D is wrong because clustering groups data but cannot predict exact bandwidth usage; prediction requires regression models. Option E is wrong because predictive analytics in network operations leverages machine learning models, not solely static thresholds defined by administrators.

Exam trap

Cisco often tests the distinction between supervised and unsupervised learning by pairing a correct application (e.g., anomaly detection) with a plausible but incorrect application (e.g., clustering for exact prediction), so candidates must remember that clustering groups data without predicting specific values.

Why the other options are wrong

C

This is incorrect because spam classification is a supervised learning problem, not a reinforcement learning one.

D

This is incorrect because clustering groups data, it doesn't forecast numeric values like bandwidth usage.

E

This is incorrect because predictive analytics typically involves dynamic ML models, not just static thresholds.

1253
MCQmedium

Which security concept is most closely associated with ensuring data has not been altered in an unauthorized way?

A.Integrity
B.Availability
C.Accounting
D.Confidentiality
AnswerA

Integrity is the security property that guarantees data has not been altered, destroyed, or tampered with by unauthorized entities during storage or transmission. Mechanisms such as hashing algorithms, message authentication codes, and digital signatures allow a system to detect any modification to the original content. Therefore, when ensuring that information remains unmodified, integrity is the relevant CIA attribute.

Why this answer

The concept is integrity. In plain language, integrity is about making sure data remains accurate and trustworthy and that unauthorized changes can be detected or prevented. If confidentiality is about stopping the wrong people from seeing data, integrity is about stopping the wrong people from changing it. Availability, meanwhile, focuses on access to systems and services when needed.

This distinction matters because CCNA questions often group security vocabulary together and rely on candidates to separate them cleanly. Integrity is not the same as authentication or accounting, and it is not simply about whether a service is online. It specifically focuses on the correctness and trustworthiness of data or system state. That is why integrity is the correct answer here.

Exam trap

A frequent exam trap is mistaking confidentiality for integrity because both relate to data security. Confidentiality prevents unauthorized users from viewing data, but it does not guarantee that the data has not been altered. Another trap is confusing availability with integrity; availability ensures systems and data are accessible when needed but does not protect against unauthorized changes.

Candidates might also select accounting, which tracks user activity but does not ensure data correctness. Understanding these distinctions is crucial to avoid selecting the wrong security concept under exam pressure.

Why the other options are wrong

B

Availability is incorrect because it focuses on ensuring that systems and data are accessible when needed, not on preventing unauthorized data modification.

C

Accounting is incorrect since it involves logging and tracking user activities and network events but does not guarantee that the data itself has not been altered.

D

Confidentiality is incorrect because it protects data from unauthorized disclosure but does not ensure that the data has not been changed or tampered with.

When would these options actually be correct?

B

In a question that asks about the importance of maintaining uptime and access to data during a cyber attack, where the focus is on ensuring users can access their data without interruption, 'Availability' would be the correct answer.

C

If the exam question asked about the importance of tracking user actions for compliance and auditing purposes, then 'Accounting' would be the correct answer. For example, a question could ask which concept helps ensure that all actions taken by users are logged for accountability.

D

If the question were to ask about which security concept is most closely associated with protecting sensitive information from unauthorized disclosure, then 'Confidentiality' would be the correct answer. For example, a question could focus on data encryption methods that prevent unauthorized access.

Why candidates pick the wrong answer

B

Candidates may confuse availability with integrity due to the interconnected nature of security concepts, mistakenly believing that ensuring access to data also implies that the data remains unaltered.

C

Candidates may confuse accounting with data integrity because both concepts involve monitoring and managing information. The overlap in their roles in security can lead to the misconception that accounting also pertains to preventing unauthorized data changes.

D

Candidates may confuse confidentiality with integrity due to their interconnected nature in security frameworks, leading them to mistakenly believe that protecting data from unauthorized access also implies preventing unauthorized alterations.

1254
MCQmedium

A team wants to know which internal hosts are sending the most traffic to a specific data center subnet. Which technology is most directly associated with that visibility goal?

A.NetFlow
B.Syslog
C.DHCP
D.PortFast
AnswerA

This is correct because NetFlow is designed to provide traffic-flow visibility.

Why this answer

NetFlow is the best fit because it provides visibility into traffic flows and conversations. In practical terms, it helps answer questions like who is talking to whom, over which protocols and ports, and how much traffic is being exchanged. That makes it useful for capacity, troubleshooting, and unusual-traffic analysis.

This is different from Syslog, which reports device events, and from general SNMP polling, which focuses more on device and interface counters.

Exam trap

A common exam trap is selecting Syslog or DHCP when asked about traffic visibility. Syslog focuses on logging system events and device messages, not on analyzing who is sending traffic or how much. DHCP is solely for IP address assignment and does not provide any traffic flow data.

Candidates might confuse these because they are familiar Cisco technologies, but neither provides the flow-level traffic insight that NetFlow offers. Misunderstanding the purpose of these protocols leads to incorrect answers, especially under time pressure.

Why the other options are wrong

B

Syslog is incorrect because it focuses on logging device events and messages rather than providing traffic flow or volume information necessary for identifying heavy traffic sources.

C

DHCP is incorrect since it only assigns IP addresses and network settings to hosts and does not offer any insight into traffic patterns or flow data.

D

PortFast is incorrect because it is a Spanning Tree Protocol feature that accelerates port forwarding state transitions and does not relate to traffic monitoring or analysis.

When would these options actually be correct?

B

If the question were about monitoring system logs for security events or troubleshooting network devices, Syslog would be the correct answer. For example, a question asking which technology is best for collecting and analyzing logs from network devices to detect anomalies would make Syslog the appropriate choice.

C

If the exam question asked about identifying which hosts are obtaining IP addresses from a DHCP server or tracking IP address leases, then DHCP would be the correct answer. This would focus on IP address management rather than traffic analysis.

D

If the question were about optimizing switch port configurations for rapid connectivity in a network where traffic patterns are less critical, PortFast would be the correct answer. For example, a question asking about reducing the time it takes for a port to become active after being connected could correctly point to PortFast.

Why candidates pick the wrong answer

B

Candidates might choose Syslog because they associate it with network monitoring and management, thinking it could provide insights into traffic patterns through log data, despite its primary function being event logging.

C

Candidates may confuse DHCP's role in network management with traffic monitoring, mistakenly believing that it can provide insights into traffic patterns based on IP address assignments.

D

Candidates might confuse the need for traffic management with port configuration features, thinking that optimizing port states could somehow relate to traffic visibility, leading them to select PortFast.

1255
MCQhard

After configuring DHCP snooping on VLAN 10 to prevent rogue DHCP servers, all clients in the VLAN stop receiving DHCP offers from the legitimate DHCP server that is connected to port Gi0/1. The administrator verifies the DHCP server is operational and reachable. What should the technician do next?

A.Enable Dynamic ARP Inspection on VLAN 10.
B.Configure interface Gi0/1 as a DHCP snooping trusted port.
C.Add an ip helper-address on the VLAN 10 SVI pointing to the DHCP server.
D.Reconfigure the DHCP server scope to include DHCP Option 82.
AnswerB

DHCP snooping treats all ports as untrusted by default and drops DHCP server messages (OFFER, ACK) that arrive on untrusted ports. The DHCP server is connected to interface Gi0/1, so the switch is currently dropping its valid reply. By configuring Gi0/1 as a DHCP snooping trusted port, the switch will forward DHCP offers and acknowledgments from that port, allowing clients on VLAN 10 to obtain addresses while still protecting against rogue DHCP servers on other ports.

Why this answer

DHCP snooping, by default, treats all ports as untrusted and drops DHCP server messages (OFFER, ACK) received on untrusted ports. Since the legitimate DHCP server is connected to Gi0/1, that port must be explicitly configured as a DHCP snooping trusted port using the 'ip dhcp snooping trust' interface command to allow DHCP server responses to reach clients.

Exam trap

Cisco often tests the default behavior of DHCP snooping where all ports are untrusted, and the trap is that candidates may think the issue is a routing problem (ip helper-address) or a server-side configuration (Option 82) rather than recognizing the need to mark the server-facing port as trusted.

Why the other options are wrong

A

Misunderstanding that DAI controls DHCP traffic rather than ARP packets.

C

Assuming DHCP snooping introduces routing changes or that the server is on a different subnet.

D

Confusing DHCP snooping with DHCP relay agent functionality and option 82 insertion.

1256
Matchingeasy

Match each HTTP method to its common REST API action.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts
Matches

Retrieve a resource

Create a new resource

Update or replace a resource

Remove a resource

Why these pairings

GET retrieves data; POST creates; PUT replaces; PATCH partially updates; DELETE removes; OPTIONS queries available methods.

Exam trap

Be careful not to confuse PUT (full replacement) with PATCH (partial update). Also, remember that GET is read-only and should not create or modify data.

When would these options actually be correct?

B

This option would be correct if the question asked about a non-standard or custom API where GET is used to create a resource (e.g., a legacy system or a poorly designed API that uses GET for creation).

C

If the question asked 'Which HTTP method is used to submit data to a server for processing, often resulting in the retrieval of a representation of the result?', then POST would be correct for actions like submitting a search query that returns results.

D

In a question asking 'Which HTTP method is used to fully update an existing resource?', PUT would be the correct answer, as it replaces the entire resource with the provided representation.

Why candidates pick the wrong answer

B

Candidates may confuse HTTP methods due to lack of practice or mistakenly think GET can create data because they have seen GET requests with query parameters that trigger server-side actions.

C

Candidates may confuse POST with GET when they think of 'posting' a request to retrieve data, or they might recall that POST can return a response body, leading them to incorrectly associate it with retrieval.

D

Candidates may confuse PUT with PATCH, especially if they have experience with APIs where PUT is used for updates without distinguishing between full and partial updates.

1257
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure AAA with a RADIUS server and enable 802.1X port authentication on a Cisco IOS-XE switch.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps
Order
1Step 1
2Step 2
3Step 3
4Step 4

Why this order

First enter global config, then define the RADIUS server, then configure AAA authentication, then enable 802.1X globally, and finally apply per-interface 802.1X settings.

Exam trap

Do not confuse the order: the RADIUS server must be defined before AAA authentication, and AAA must be configured before enabling 802.1X globally. A common trap is to enable 802.1X too early.

Why candidates pick the wrong answer

B

Candidates might think 802.1X can be enabled globally at any time, but AAA must be ready before 802.1X can function.

C

Candidates might think AAA authentication configuration is independent of server definition, but it requires the server group to be defined.

D

Candidates might think 802.1X global enablement is independent of AAA, but it relies on AAA for authentication.

1258
MCQmedium

An engineer wants users to get fast link-up on access ports but also wants the switch to disable a port if another switch is connected and sends BPDUs. Which combination of features best meets that requirement?

A.PortFast and BPDU Guard
B.DHCP snooping and DAI
C.Root Guard and VTP pruning
D.Port security and CDP
AnswerA

PortFast bypasses the spanning-tree listening and learning states, allowing a host-facing access port to transition directly to forwarding and deliver immediate link-up. BPDU Guard complements this by shutting the port in an error-disabled state if any BPDU is received, which blocks an accidental or rogue switch connection while preserving the fast-start behavior for legitimate hosts. Together they form the standard Cisco edge-port hardening pair.

Why this answer

PortFast and BPDU Guard are the classic edge-port combination for this requirement. PortFast helps a user-facing interface begin forwarding quickly so a PC or phone does not wait through the normal spanning-tree transition delay. BPDU Guard adds protection by monitoring that same port for BPDUs.

If a switch is accidentally or intentionally connected and starts participating in spanning tree, BPDU Guard reacts by disabling the port to protect the Layer 2 topology. In plain language, users get quick connectivity when the port is used correctly, but the network still protects itself against someone plugging in a switch where only an endpoint should exist. That is exactly what the requirement asks for.

Exam trap

Avoid confusing BPDU Guard with other guard features like Root Guard or Loop Guard, which serve different purposes.

Why the other options are wrong

B

DHCP snooping and DAI (Dynamic ARP Inspection) do not address the requirement of disabling a port upon receiving BPDUs; they focus on protecting against rogue DHCP servers and ARP spoofing, respectively.

C

Root Guard and VTP pruning do not address the requirement of quickly enabling access ports and disabling them upon receiving BPDUs. Root Guard is used to prevent a port from becoming a root port, while VTP pruning optimizes VLAN traffic, neither of which directly manage port states based on BPDU reception.

D

Port security and CDP do not provide the necessary functionality to disable a port when BPDUs are received. Port security can limit the number of MAC addresses but does not specifically address BPDU handling.

When would these options actually be correct?

B

If the exam question asked for features to enhance network security and prevent unauthorized DHCP servers while ensuring valid DHCP traffic, then DHCP snooping and DAI would be the correct answer, as they work together to secure the DHCP infrastructure.

C

If the exam question focused on maintaining the stability of the spanning tree topology in a multi-switch environment while allowing for efficient VLAN management, then Root Guard could be the correct answer. For instance, a scenario where the goal is to prevent a switch from becoming the root bridge would make this option valid.

D

If the exam question asked for a method to secure access ports against unauthorized devices while also enabling monitoring of connected devices, then Port security and CDP could be the correct answer. This would focus on ensuring only known devices connect while utilizing CDP for network topology information.

Why candidates pick the wrong answer

B

Candidates may find this option tempting because both DHCP snooping and DAI are well-known security features in networking, leading them to mistakenly associate them with port protection and network integrity.

C

Candidates may choose this option because they recognize the importance of spanning tree protocols and may mistakenly believe that Root Guard's function of managing root bridge elections aligns with the need to control port states in response to BPDUs.

D

Candidates may choose this option because they recognize that Port security is a common feature for securing switch ports, and they might mistakenly believe that CDP's monitoring capabilities align with the requirements of the question.

1259
MCQhard

A router performing PAT is using a single public IPv4 address for many inside hosts. Which value most often distinguishes one inside flow from another on the same outside address?

A.TTL
B.DSCP
C.TCP or UDP source port
D.MAC address of the host
AnswerC

PAT (Port Address Translation) multiplexes many internal hosts onto a single public IPv4 address by rewriting the transport-layer source port. Each active flow is uniquely identified by the combination of the public IP, the source port, and the destination IP/port, allowing the router to reverse the translation and deliver return traffic to the correct internal host. Without port differentiation, all internal hosts would appear as the same IP with no way to distinguish their connections.

Why this answer

PAT commonly multiplexes sessions by translating Layer 4 source port numbers.

Exam trap

A common exam trap is selecting TTL or DSCP as the distinguishing value for inside flows in PAT. TTL is often mistaken because it changes during routing, but it does not uniquely identify sessions. DSCP is related to Quality of Service and does not influence NAT translations.

Another trap is thinking MAC addresses can be used to differentiate flows; however, MAC addresses are stripped and replaced at each routed hop, so they are irrelevant in PAT. The correct distinguishing factor is the TCP or UDP source port number, which PAT uses to multiplex multiple inside hosts over a single public IP address.

Why the other options are wrong

A

TTL is not the main distinguishing value PAT uses because it changes as packets traverse routers and does not uniquely identify individual flows in NAT translations.

B

DSCP is a QoS marking used to prioritize traffic and does not play a role in NAT or PAT flow differentiation, so it cannot distinguish inside flows sharing one outside IP.

D

MAC addresses are Layer 2 addresses that are not preserved across routed NAT boundaries, so they cannot be used to distinguish flows in PAT.

When would these options actually be correct?

A

In a different question, if it asked about identifying the characteristics of packets in a network where multiple packets from the same source IP are being analyzed, TTL could be relevant in discussing how long packets remain valid in the network before being discarded.

B

In a scenario where the question asks about traffic management and prioritization for Quality of Service (QoS) in a network, DSCP could be the correct answer if the focus is on how packets are treated based on their DSCP values rather than on NAT or PAT operations.

D

In a question focused on local area network (LAN) segmentation or device identification, where MAC addresses are relevant for distinguishing devices within the same subnet, this option would be correct. For example, a question might ask which identifier is used to manage traffic within a switched network environment.

Why candidates pick the wrong answer

A

Candidates may confuse TTL with flow identification due to its role in routing and packet management, mistakenly believing it could serve as a unique identifier for different sessions or flows.

B

Candidates may confuse DSCP with flow identification due to its role in managing traffic and might mistakenly believe it plays a part in distinguishing flows in NAT scenarios, leading to the selection of this option.

D

Candidates may be tempted to choose this option because they associate MAC addresses with unique device identification, leading them to mistakenly believe it applies to traffic management in NAT scenarios.

1260
Drag & Dropmedium

Drag and drop the following OSPFv2 neighbor state transitions into the correct order, starting from the initial state when no neighbor information has been received.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps
Order
1Step 1
2Step 2
3Step 3
4Step 4

Why this order

OSPF neighbor states begin at Down, then Init after receiving Hello, 2-Way after seeing own router ID, ExStart for master/slave negotiation, and Exchange for exchanging database descriptors.

Exam trap

Do not confuse the order of ExStart and Exchange; ExStart always precedes Exchange. Also, remember that 2-Way comes after Init, not before.

Why candidates pick the wrong answer

B

Candidates might confuse the sequence if they think bidirectional communication happens immediately after receiving any Hello.

C

Candidates may think database descriptor exchange starts immediately after Init, skipping the 2-Way state.

D

Candidates might assume that exchanging database descriptors happens before negotiating master/slave roles.

1261
MCQmedium

Which HTTP method is typically used to retrieve data from a REST API without modifying the resource?

A.POST
B.PUT
C.GET
D.DELETE
AnswerC

GET is a safe and idempotent HTTP method that requests a representation of a specific resource without modifying server state. In REST design, it is the standard method for read-only operations such as fetching a resource or collection. Because it has no side effects, GET responses can be cached and repeated safely.

Why this answer

GET requests are used to retrieve resource information. They are intended for read operations rather than creation, replacement, or deletion.

Exam trap

A common exam trap is confusing the GET method with POST or PUT because all involve interacting with REST API resources. Candidates might incorrectly select POST or PUT, thinking they retrieve data, but POST is primarily for creating resources and PUT for updating them. GET is unique because it only retrieves data without changing the resource.

Misunderstanding this can lead to selecting an incorrect method that modifies the network device state, which is not the intent of the question. Remember, GET is the only method designed to safely fetch data without side effects.

Why the other options are wrong

A

POST is incorrect because it is used to create new resources or submit data that modifies the server state, not for retrieving existing data. Selecting POST would imply changing the resource, which contradicts the question's requirement for a non-modifying method.

B

PUT is incorrect as it replaces or updates an existing resource entirely. It modifies the resource state, which is not the intended action when simply retrieving data from a REST API.

D

DELETE is incorrect because it removes a resource from the server. Using DELETE would modify the resource by deleting it, which is the opposite of the question's intent to retrieve data without modification.

When would these options actually be correct?

A

In a different exam scenario, a question might ask which HTTP method is used to submit data to a server for processing, such as creating a new user account or submitting a form. In that context, POST would be the correct answer.

B

In a different question asking which HTTP method is used to update an existing resource in a REST API, PUT would be the correct answer. For example, a question could specify that the method is intended to replace the entire resource representation.

D

If the question asked which HTTP method is used to remove a resource from a REST API, then DELETE would be the correct answer. This scenario would focus on resource management rather than data retrieval.

Why candidates pick the wrong answer

A

Candidates may choose POST because they associate it with data operations and may overlook the specific requirement of retrieval, leading to confusion between methods that handle data submission versus data retrieval.

B

Candidates may confuse PUT with GET due to their similar roles in RESTful services, especially if they are not fully clear on the distinction between retrieving and modifying resources.

D

Candidates may confuse DELETE with data retrieval due to the common misconception that all HTTP methods can be used interchangeably, especially if they are familiar with RESTful principles but not the specific functions of each method.

1262
MCQmedium

Exhibit: A network engineer wants to identify which applications are consuming most WAN bandwidth over time. Which feature should be enabled on the router?

A.NTP authentication
B.NetFlow
C.DNS forwarding
D.DHCP snooping
AnswerB

NetFlow is a flow-based telemetry technology on Cisco devices that captures packet metadata such as source and destination IP addresses, port numbers, protocol, and byte counts, aggregating them into unidirectional or bidirectional flows. By analyzing these flow records, an engineer can identify applications by matching well-known port numbers or using NBAR to classify application signatures, making it ideal for application visibility and traffic profiling.

Why this answer

NetFlow records conversations and traffic characteristics so an external collector can analyze top talkers, protocols, and usage trends. Syslog and SNMP have different purposes.

Exam trap

A frequent exam trap is mistaking features like DHCP snooping or DNS forwarding as tools for bandwidth monitoring. DHCP snooping is a Layer 2 security mechanism that prevents unauthorized DHCP servers but does not provide traffic usage data. DNS forwarding helps resolve domain names faster but does not track or analyze bandwidth consumption.

Another trap is confusing NTP authentication, which secures time synchronization, with traffic profiling tools. Candidates must recognize that only NetFlow collects detailed flow information necessary to identify which applications consume the most WAN bandwidth over time.

Why the other options are wrong

A

NTP authentication protects the integrity of time synchronization between devices but does not provide any mechanism for monitoring or analyzing network traffic flows or bandwidth usage.

C

DNS forwarding improves domain name resolution efficiency but does not collect or analyze traffic flow information related to bandwidth consumption.

D

DHCP snooping is a security feature that prevents unauthorized DHCP servers at Layer 2 and does not provide any traffic profiling or bandwidth monitoring capabilities.

When would these options actually be correct?

A

If the exam question asked about securing time synchronization in a network environment where accurate timekeeping is critical for logging and auditing purposes, NTP authentication would be the correct answer. For example, a scenario focusing on preventing time-based attacks would make this option valid.

C

If the exam question asked about optimizing DNS resolution times or troubleshooting DNS-related issues in a network, enabling DNS forwarding could be the correct answer, as it would help improve the efficiency of DNS queries.

D

If the exam question asked about securing a network against rogue DHCP servers or ensuring that only trusted DHCP responses are accepted, DHCP snooping would be the correct answer. This would focus on maintaining network integrity rather than monitoring bandwidth.

Why candidates pick the wrong answer

A

Candidates may confuse NTP's role in network operations, thinking that time synchronization could somehow relate to bandwidth monitoring, especially if they are not fully aware of specific features like NetFlow that directly address traffic analysis.

C

Candidates may confuse DNS forwarding with network monitoring tools, mistakenly believing that it could help analyze traffic patterns, especially if they are not fully aware of the specific functions of each network feature.

D

Candidates may confuse DHCP snooping with network monitoring features due to their shared context in network management, leading them to mistakenly believe it could help in assessing bandwidth usage.

1263
Multi-Selectmedium

Which four of the following correctly describe how AI/ML techniques can improve network operations in a modern enterprise? (Choose all that apply.)

Select 4 answers
.AI models can analyze historical traffic data to predict future bandwidth congestion
.Natural language processing (NLP) can be used to automate responses to helpdesk tickets based on intent
.Reinforcement learning can adjust firewall rules dynamically in response to evolving attack patterns
.Unsupervised learning can identify unknown device types on the network by clustering behavior patterns
.AI eliminates the need for baseline performance metrics because it learns in real-time
.ML models always require labeled training data to be effective in network operations

Why this answer

Options A, B, C, and D are correct. AI models can predict bandwidth congestion by analyzing historical traffic data, enabling proactive capacity planning. Natural language processing (NLP) automates helpdesk ticket responses by interpreting user intent, reducing manual effort.

Reinforcement learning can dynamically adjust firewall rules in response to evolving attack patterns, improving threat response without human intervention. Unsupervised learning can cluster behavior patterns to identify unknown device types on the network. Option E ("AI eliminates the need for baseline performance metrics because it learns in real-time") is incorrect because even AI/ML models require baseline metrics to establish normal behavior and detect anomalies; real-time learning does not remove the need for baselines.

Option F ("ML models always require labeled training data to be effective in network operations") is incorrect because many ML techniques, such as unsupervised learning (as shown in option D), operate effectively on unlabeled data by discovering patterns and clusters without predefined labels.

Exam trap

Cisco often tests the breadth of AI/ML applications in network operations, and the trap here is that candidates might dismiss reinforcement learning as too advanced or theoretical, but it is a valid technique for dynamic policy adjustment in modern intent-based networking (IBN) systems.

1264
MCQhard

Why is traffic to 10.10.10.200 using the EIGRP route instead of the OSPF route, given that both routes have the same prefix length?

A.Because EIGRP has a lower administrative distance than OSPF for the same prefix length.
B.Because OSPF routes are never installed when EIGRP is present.
C.Because OSPF can be used only for IPv6 routes.
D.Because EIGRP routes always have a smaller subnet mask than OSPF routes.
AnswerA

Both EIGRP and OSPF have learned routes to 10.10.10.0/24, so the prefix lengths are identical, meaning longest-match selection does not break the tie. Cisco's default administrative distance for internal EIGRP is 90, while OSPF's is 110; since lower AD is preferred, the EIGRP route is installed in the routing table. This is the correct explanation of why traffic to 10.10.10.200 uses the EIGRP path.

Why this answer

When two routes have the same prefix length, the router uses administrative distance to choose the route with the lowest value. EIGRP has a default administrative distance of 90, while OSPF uses 110. Therefore, the EIGRP route is preferred.

Exam trap

A common mistake is to assume that OSPF routes always have a lower administrative distance than EIGRP routes.

Why the other options are wrong

B

OSPF routes are installed when EIGRP is present; routing protocols coexist and the route with the lowest AD is selected.

C

OSPF supports both IPv4 and IPv6; it is not limited to IPv6.

D

EIGRP routes do not always have a smaller subnet mask; prefix length is determined by the network design, not the routing protocol.

When would these options actually be correct?

B

In a scenario where the question specifies that OSPF is configured to not participate in routing due to a specific configuration, such as a route map or filtering, this option could be correct. For example, if the question stated that OSPF was disabled or not operational, then EIGRP would be the only routing protocol providing routes.

C

In a different scenario where the question specifies that only IPv6 routing protocols are being considered, and the traffic is directed to an IPv6 address, this option could be correct if the question implies that OSPF is not configured for IPv6 routes.

D

In a different scenario where the question specifies that EIGRP routes are always configured with a smaller subnet mask than OSPF routes, and the routing decision is based solely on the mask size, this option could be correct. For example, if the question asked why a specific route was preferred due to subnet mask comparison, then this option would apply.

Why candidates pick the wrong answer

B

Candidates may choose this option due to a misunderstanding of how routing protocols interact, mistakenly believing that the presence of one protocol inherently prevents the installation of routes from another.

C

Candidates may choose this option due to a misunderstanding of OSPF's capabilities, mistakenly believing that it is limited to IPv6, especially if they have encountered questions focused solely on IPv6 routing.

D

Candidates may choose this option due to a common misconception that EIGRP's efficiency is tied to its subnet mask size, leading them to overlook the fundamental routing decision factor of administrative distance.

1265
Multi-Selectmedium

Which TWO switch port configurations are required when connecting a Cisco IP phone and a desktop PC to a single access port?

Select 2 answers
A.Configure the port as a trunk and allow both VLANs.
B.Use the 'switchport voice vlan' command to assign a dedicated voice VLAN.
C.Disable spanning tree on the port to prevent voice delays.
D.Apply 'mls qos trust cos' on the interface to preserve voice packet markings.
E.Configure the port as a routed port with an IP address for management.
AnswersB, D

The 'switchport voice vlan' command is the correct method because it configures an access port to carry both data and voice while keeping them logically separate. The Cisco IP phone uses CDP or LLDP to learn the configured voice VLAN, tags all voice frames with that VLAN's 802.1Q header, and passes the PC's untagged traffic in the access VLAN. This preserves the normal access port behavior for the connected PC while ensuring voice traffic is segmented for QoS and security.

Why this answer

The 'switchport voice vlan' command assigns a dedicated VLAN for voice traffic, allowing the IP phone to tag its packets with the voice VLAN ID while the PC remains in the native (data) VLAN. Option D is correct because 'mls qos trust cos' preserves the Layer 2 Class of Service (CoS) markings from the IP phone, ensuring voice packets receive appropriate QoS treatment across the network. Option A is incorrect because a trunk port is not required—the access port with the voice VLAN command handles both VLANs without trunking.

Option C is incorrect because disabling Spanning Tree Protocol (STP) is not a recommended practice and does not prevent voice delays; STP is essential for loop prevention and can be tuned with PortFast instead. Option E is incorrect because the port must remain a Layer 2 access port, not a routed port, to support both the PC and IP phone.

Exam trap

Cisco often tests the misconception that a trunk port is needed to carry both voice and data VLANs, but the correct approach uses a single access port with the 'switchport voice vlan' command to handle both VLANs without trunking.

Why the other options are wrong

A

Using a trunk port for a single device connection is unnecessary and violates standard access port design; it would also require the phone to support trunking, which is not the typical Cisco IP phone configuration.

C

STP does not introduce significant delays in normal operation, and disabling it risks broadcast storms and network loops.

E

Access ports operate at Layer 2; converting to a routed port would prevent the phone and PC from communicating within their respective VLANs.

1266
Multi-Selectmedium

Which TWO statements about IPv4/IPv6 static routing are true?

Select 2 answers
A.A floating static route is configured with a lower administrative distance than the primary route.
B.An IPv6 default static route can be configured using the destination prefix ::/0.
C.A static route with an administrative distance of 1 is preferred over a directly connected route.
D.A floating static route becomes active in the routing table only when the primary route is removed or fails.
E.IPv4 and IPv6 static routes are configured using the same command syntax.
AnswersB, D

The IPv6 default static route uses the destination prefix ::/0, which matches any IPv6 address, analogous to IPv4's 0.0.0.0/0. It is commonly configured with the command 'ipv6 route ::/0' followed by a next-hop address or exit interface. This allows the router to forward all unmatched IPv6 traffic to a designated gateway.

Why this answer

The IPv6 default static route uses the destination prefix ::/0, which matches all IPv6 addresses, similar to 0.0.0.0/0 in IPv4. Option D is correct because a floating static route is configured with a higher administrative distance and only becomes active when the primary route (with a lower AD) is removed or fails. Option A is wrong: a floating static route is configured with a higher administrative distance, not lower.

Option C is wrong: a directly connected route has an administrative distance of 0, which is always preferred over a static route (even with AD 1). Option E is wrong: IPv4 static routes use the 'ip route' command, while IPv6 static routes use the 'ipv6 route' command; the syntax is different.

Exam trap

Cisco often tests the inverse relationship between administrative distance and route preference, trapping candidates who think a lower AD makes a route less preferred rather than more preferred.

Why the other options are wrong

A

A floating static route is configured with a higher administrative distance than the primary route, not lower.

C

A directly connected route has an administrative distance of 0, which is preferred over a static route with AD 1.

E

IPv4 static routes use the 'ip route' command, while IPv6 static routes use the 'ipv6 route' command; the syntax is different.

1267
MCQhard

A small office uses PAT for user Internet access. What mechanism does PAT use to allow many users to share one public address while keeping their sessions distinct?

A.Use transport-layer port values to distinguish multiple inside sessions behind one outside address.
B.Convert all inside hosts to the same private IP address.
C.Increase the size of the NAT pool to include multiple public addresses.
D.Configure static NAT mappings for each inside host.
AnswerA

Port Address Translation (PAT) multiplexes thousands of internal hosts through a single public IPv4 address by rewriting the source port along with the source IP in each packet. The NAT router builds a session table that maps each inside local address and TCP/UDP port to the outside global address plus a unique translated port, allowing return traffic to be correctly demultiplexed. This is exactly how one outside address can simultaneously support many inside sessions.

Why this answer

PAT (Port Address Translation) distinguishes multiple inside sessions by rewriting the source port number for each connection while using the same public IP address. This transport-layer port translation allows many internal hosts to share one outside address without conflict. The correct answer identifies the use of port numbers, which is the core mechanism.

Increasing the NAT pool or using static NAT would not enable sharing of a single public address. Changing private IPs to be identical or disabling routes are irrelevant to PAT's operation.

Exam trap

A common mistake is thinking PAT requires all inside hosts to have the same private IP or that adding more public IPs is the primary method for sharing a single address.

Why the other options are wrong

B

Converting all inside hosts to the same private IP would cause addressing conflicts and break basic connectivity, not enable PAT.

C

Increasing the NAT pool provides more public addresses but does not allow many users to share one public address via port translation.

D

Static NAT requires a dedicated public IP per host, preventing many-to-one sharing.

When would these options actually be correct?

B

In a scenario where a question asks how to simplify IP address management in a small network with only one device needing external access, and all devices are in a trusted environment, this option could be correct if it implies using a single private IP for a specific application or service.

C

In a different scenario where the question asks about isolating internal traffic for security purposes, disabling the default route could be correct if the goal is to ensure that internal hosts do not communicate with the outside world, thereby enhancing security.

D

In a scenario where the question asks about optimizing VLAN configurations for multiple subnets to communicate over a single physical link, changing access ports to trunk ports would be correct to allow multiple VLANs to share the same infrastructure while maintaining separation.

Why candidates pick the wrong answer

B

Candidates may find this option tempting because it suggests a simplified approach to IP management, which can seem appealing in small networks, leading them to overlook the implications of session management and address conflicts.

C

Candidates may find this option tempting because it suggests a method to control traffic flow, which can be appealing when considering network management and security, despite it not addressing the requirement for shared public address access.

D

Candidates may be tempted by this option due to familiarity with VLAN concepts and the assumption that trunking could somehow enhance network efficiency, leading them to overlook the specific requirement of session distinction in NAT configurations.

1268
MCQhard

A network engineer notices that after adding a new switch to the network, a different switch unexpectedly becomes the STP root bridge, disrupting all VLANs. The new switch has the default priority (32768) but has a lower MAC address than all existing switches. What is the most likely cause?

A.The new switch is running PVST+ while the existing switches use Rapid PVST+
B.Root Guard is enabled on the new switch’s uplink ports facing the existing root
C.The existing root bridge has a bridge priority lower than the default value of 32768
D.The new switch was added with a bridge priority of 4096
AnswerC

If the existing root bridge’s priority is less than 32768 (e.g., 4096 or 0), its Bridge ID is lower than the new switch’s default 32768 + lower MAC. STP always elects the switch with the lowest Bridge ID as the root bridge. Thus, despite the new switch’s lower MAC, the manually lowered priority keeps the existing switch as root.

Why this answer

The existing root bridge has a bridge priority lower than the default value of 32768, so even though the new switch has the default priority, its lower MAC address does not make it the root. STP elects the root bridge based on the lowest bridge ID (priority + MAC address). Since the existing root already has a lower priority, it remains the root.

The new switch's lower MAC address only becomes a tiebreaker when priorities are equal, which is not the case here.

Exam trap

Cisco often tests the misconception that a lower MAC address alone can cause a root bridge change, but the trap here is that candidates forget the bridge priority is compared first, so a switch with default priority cannot outrank an existing root with a manually lowered priority.

Why the other options are wrong

A

Candidates may think that STP version incompatibility disrupts root election, but both versions use the same BPDU format and root election rules.

B

Candidates often associate Root Guard with preventing a switch from becoming the root. However, it does not cause another switch to become root; it just protects the network from unexpected superior BPDUs.

D

Candidates may confuse the symptom and think that a low priority on the new switch causes the problem, but this would make the new switch the root, not another switch.

1269
MCQhard

Based on the exhibit, what is the most likely reason the PPP link is failing to authenticate?

A.The PPP authentication credentials do not match between the two sides.
B.The interfaces must use HDLC instead of PPP before authentication can work.
C.CHAP requires the routers to be in different IPv4 subnets.
D.PPP authentication works only over GRE tunnels.
AnswerA

CHAP authentication relies on a shared secret that must be identical on both routers. The exhibit shows the CHAP password configured on one side is different from the other, so the hash computed during the challenge-response handshake will not match and the PPP link will fail authentication. Without matching credentials, the link cannot transition to the established state.

Why this answer

The most likely reason is a credentials mismatch between the two sides of the PPP authentication setup. In practical terms, PPP authentication requires the peers to agree on the relevant identity and secret information. If those values do not align, the link may come up physically but authentication fails and the logical connection does not establish properly.

This is a very exam-relevant WAN troubleshooting scenario because it focuses on a realistic failure after the transport is already present.

Exam trap

Be careful not to confuse physical link issues with authentication problems. Just because the link is up doesn't mean authentication is successful.

Why the other options are wrong

B

This option is incorrect because PPP (Point-to-Point Protocol) does not require HDLC (High-Level Data Link Control) for authentication; PPP can authenticate independently of the encapsulation method used.

C

This option is incorrect because CHAP (Challenge Handshake Authentication Protocol) does not require routers to be in different IPv4 subnets for authentication to function. CHAP can authenticate devices regardless of their subnet configuration as long as they can reach each other over the network.

D

This option is incorrect because PPP (Point-to-Point Protocol) can operate independently of GRE (Generic Routing Encapsulation) tunnels; authentication can occur directly over a PPP link without requiring GRE.

When would these options actually be correct?

B

In a different scenario where a question specifies that a network is configured to use HDLC for link-layer encapsulation and requires authentication, a candidate might be asked about the compatibility of HDLC with authentication methods, making this option correct.

C

In a different exam scenario, a question might specify that CHAP authentication is being tested in a network where the routers are indeed in different IPv4 subnets, and the question could ask about the implications of such a configuration on CHAP's functionality. In this case, the option could be correct if it stated that subnet differences affect routing or connectivity, not CHAP itself.

D

In a different question scenario where the context specifies that the authentication method is limited to GRE tunnels, and the question asks about the feasibility of PPP authentication in that specific setup, this option could be correct.

Why candidates pick the wrong answer

B

Candidates may find this option tempting because they might confuse the encapsulation methods and assume that HDLC is a prerequisite for any authentication process, leading to the misconception that PPP cannot function without it.

C

Candidates may choose this option due to a misunderstanding of how network protocols interact with IP addressing, leading them to incorrectly associate subnetting with authentication requirements.

D

Candidates may find this option tempting because they might confuse the functionalities of PPP and GRE, thinking that authentication mechanisms are tied to specific encapsulation methods, leading to misconceptions about their interoperability.

1270
MCQhard

A user reports that they cannot access a remote server at IP address 10.10.20.50. The user's PC has IP address 192.168.1.25/24, and the default gateway is 192.168.1.1. The user can successfully ping the default gateway and other hosts on the local subnet. However, pings to 10.10.20.50 fail, and a traceroute shows only the first hop (192.168.1.1) followed by timeouts. Which of the following is the most likely cause?

A.The user's PC has an incorrect subnet mask.
B.The default gateway lacks a route to the 10.10.20.0/24 network.
C.The remote server at 10.10.20.50 is powered off.
D.The user's DNS server is unreachable.
AnswerB

Since the client can ping the gateway but traceroute fails immediately after the first hop, the gateway does not know how to forward packets to 10.10.20.0/24. It either drops the packets or returns an ICMP destination unreachable, causing the observed behavior.

Why this answer

The user can reach local hosts and the default gateway, confirming that the PC's IP configuration and local switching are functional. The traceroute stopping at 192.168.1.1 with subsequent timeouts indicates that the default gateway receives the packets but does not know how to forward them to the 10.10.20.0/24 network. Therefore, the most likely cause is that the default gateway lacks a route to that remote subnet.

Exam trap

Cisco often tests the distinction between local connectivity issues (subnet mask, ARP) and routing issues (missing routes), trapping candidates who assume a failed ping to a remote IP must be due to the destination being down or a DNS problem.

Why the other options are wrong

A

The user can communicate with the default gateway and other local devices, so the subnet mask is correctly configured for the local network.

C

A powered-off server would cause timeouts only after the last router before the server, not immediately after the first hop.

D

Because the user is using the server's IP address, DNS is not involved in this connectivity test.

1271
MCQmedium

A DHCP server is located on a different VLAN from the clients. Which feature is required so the clients can still receive addresses?

A.DHCP snooping
B.DHCP relay
C.Port security
D.NAT overload
AnswerB

DHCP relay is the correct solution because DHCP clients send broadcast DISCOVER messages, and routers do not forward broadcasts between VLANs. A relay agent such as an ip helper-address command on the router's SVI intercepts the broadcast, unicasts it to the DHCP server's IP, and relays the server's OFFER/ACK back to the client, enabling cross-subnet address assignment.

Why this answer

DHCP relay forwards client broadcasts to a remote server as unicast, typically using ip helper-address on the Layer 3 interface.

Exam trap

A common exam trap is selecting DHCP snooping as the solution for clients on different VLANs to receive DHCP addresses. DHCP snooping is a security mechanism that filters DHCP messages to prevent rogue servers but does not forward DHCP broadcasts across VLANs. Another tempting but incorrect choice is port security, which controls MAC address access on switch ports but does not affect DHCP broadcast forwarding.

NAT overload is unrelated to DHCP address assignment and only translates IP addresses for outbound traffic. The key misunderstanding is confusing DHCP relay’s role in forwarding broadcasts with security or address translation features.

Why the other options are wrong

A

DHCP snooping is a security feature that prevents unauthorized DHCP servers by filtering DHCP messages. It does not forward DHCP broadcasts across VLANs, so it cannot enable clients on different VLANs to receive addresses.

C

Port security restricts the number and identity of MAC addresses on switch ports to enhance security. It does not affect DHCP broadcast forwarding or enable clients to receive addresses from servers on different VLANs.

D

NAT overload translates multiple private IP addresses to a single public IP address for outbound traffic. It does not address the issue of forwarding DHCP broadcasts between VLANs or enable DHCP clients to obtain addresses from remote servers.

When would these options actually be correct?

A

In a scenario where a network administrator is asked about securing a DHCP environment, a question may ask how to prevent rogue DHCP servers while allowing legitimate ones. In this case, DHCP snooping would be the correct answer as it protects the network from unauthorized DHCP responses.

C

In a scenario where a question asks about securing a network by limiting the number of devices that can connect to a specific switch port, port security would be the correct answer. For example, if the question involves preventing unauthorized devices from accessing the network while allowing legitimate DHCP clients, port security would apply.

D

In a scenario where the question asks about enabling multiple internal devices to access the internet using a single public IP address, NAT overload would be the correct answer. This would involve a setup where clients need to communicate externally while conserving public IP addresses.

Why candidates pick the wrong answer

A

Candidates may choose this option because they associate DHCP snooping with DHCP functionality and security, mistakenly believing it plays a role in enabling clients to communicate with a DHCP server across VLANs.

C

Candidates may choose this option because they associate port security with network access control, mistakenly believing it relates to managing DHCP traffic across VLANs.

D

Candidates may confuse NAT overload with DHCP functionality, thinking that since both involve IP address management, NAT could somehow assist in DHCP address assignment across VLANs. This misconception can lead to selecting it as a viable option.

1272
MCQhard

Two switches are connected via an IEEE 802.1Q trunk. Hosts in VLAN 30 on opposite sides cannot communicate, yet hosts in VLAN 10 communicate normally. Both switches have VLAN 30 in their VLAN database, and the trunk link is operational. What is the most likely cause?

A.VLAN 30 is pruned or not allowed on one side of the trunk
B.The native VLAN must be set to 30
C.STP blocks all VLANs on the trunk when one VLAN fails
D.The trunk must be changed to access mode for VLAN 30
AnswerA

VLAN 30 is either pruned via VTP pruning or excluded by the switchport trunk allowed vlan list on at least one of the interconnected switches. Because the 802.1Q trunk carries VLAN 10 successfully, the physical link and trunk parameters are operational, but VLAN 30's frames are deliberately filtered before crossing the trunk, so hosts in VLAN 30 experience complete connectivity loss while VLAN 10 remains unaffected.

Why this answer

If a VLAN is not allowed on one side of the trunk, frames for that VLAN are dropped even though other VLANs continue to work. Option A correctly identifies that VLAN 30 is either pruned or missing from the allowed list on one end. Option B is wrong because the native VLAN only affects untagged frames and would not cause the filtering of a tagged VLAN like VLAN 30.

Option C is incorrect because STP can block individual VLANs per port, but it does not block all VLANs on a trunk due to a single VLAN’s issue—only the affected VLAN would be blocked. Option D is invalid because converting the trunk to access mode would break all VLAN trunking, including the working VLAN 10.

Exam trap

Ensure you check the trunk configuration for allowed VLANs, not just VLAN existence or port assignments.

Why the other options are wrong

B

The native VLAN setting only governs untagged traffic on the trunk, not the tagged frames of VLAN 30, so it cannot fix a missing allowed VLAN.

C

STP does not globally block all VLANs on a trunk; per‑VLAN spanning tree can block individual VLANs, but a single VLAN failure would not cause the trunk to block all traffic.

D

Changing the trunk to access mode would restrict the link to a single VLAN, breaking VLAN 10 connectivity as well, which contradicts the working state of VLAN 10.

When would these options actually be correct?

B

In a different scenario where a question specifies that all VLAN traffic must be tagged and requires the native VLAN to be set to a specific VLAN for proper communication, then setting the native VLAN to 30 would be necessary for hosts in that VLAN to communicate effectively.

C

In a different scenario, if a question stated that a trunk link was experiencing issues due to a misconfiguration where STP was incorrectly set to block all traffic, this option could be correct. For example, if the question described a network with multiple VLANs and a misconfigured STP that inadvertently blocked all VLANs due to a loop, then this option would apply.

D

In a different scenario where a question states that VLAN 30 needs to be configured for a specific access port to allow devices to connect directly to it, then changing the trunk to access mode for VLAN 30 would be correct. This would imply that VLAN 30 is intended to operate as an access VLAN rather than a trunked VLAN.

Why candidates pick the wrong answer

B

Candidates may choose this option due to a misunderstanding of the role of the native VLAN, believing that it must match the VLANs in use for communication to occur, leading to confusion about VLAN configurations.

C

Candidates may choose this option due to a misunderstanding of STP behavior, thinking that a failure in one VLAN would cause a cascading effect that impacts all VLANs on the trunk, reflecting a common misconception about STP functionality.

D

Candidates might choose this option due to a misunderstanding of VLAN configurations, believing that access mode is necessary for VLAN communication, especially if they confuse the roles of access and trunk ports.

1273
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure and apply an extended ACL that permits only HTTP traffic from the 192.168.1.0/24 network to the server at 10.0.0.1, with the ACL applied inbound on the router's GigabitEthernet0/0 interface, and then verify the configuration.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps
Order
1Step 1
2Step 2
3Step 3
4Step 4

Why this order

First, enter config mode. Create the ACL permitting HTTP from the source network to the destination host. Apply it inbound on the correct interface.

Then exit and verify.

Exam trap

Pay attention to the direction of ACL application (inbound vs outbound) and the specific verification command. Also, ensure you exit configuration mode before verifying, as some show commands are available in config mode but the standard workflow is to exit first.

Why candidates pick the wrong answer

B

Candidates might confuse inbound and outbound directions, especially if they think of traffic flowing from the source network to the server as 'outbound' from the router.

C

Candidates might think that 'show running-config' can be used in any mode, but the question expects a specific order that includes exiting configuration mode before verification.

D

Candidates might confuse 'show ip interface brief' with 'show access-lists' because both are common show commands, but they serve different purposes.

1274
MCQhard

In a controller-based design, which statement best describes a northbound API?

A.An application-facing API used by external software to communicate with the controller
B.A cable type used between controller clusters
C.The link-state protocol the controller uses to reach switches
D.A mechanism that removes the need for authentication
AnswerA

In a controller-based architecture, the northbound API (often RESTful) faces applications and orchestration systems, allowing them to request network services or retrieve telemetry without manual device-level configuration. It abstracts the underlying network complexity, so external software can communicate intent to the controller, which then translates that intent into device-specific actions. This direction is 'north' because it sits above the controller in the logical hierarchy.

Why this answer

A northbound API is the interface exposed by the controller to external applications, orchestration systems, dashboards, or automation tools. In plain language, it is the way software above the controller communicates with the controller so that it can request data, apply policy, or trigger changes. This is different from the southbound side, where the controller interacts with the underlying infrastructure devices.

This concept appears often in automation topics because it helps define where the controller sits in the larger architecture. A northbound API is not a physical cable, and it does not replace security controls. It is an application-facing software interface, which is exactly what the correct answer should capture.

Exam trap

A frequent exam trap is mistaking the northbound API for a physical cable or a routing protocol. Some candidates incorrectly associate 'northbound' with physical connections between controllers or with link-state protocols, which is incorrect. Northbound APIs are purely logical interfaces used by applications to communicate with the controller, not hardware or routing mechanisms.

Another trap is assuming northbound APIs bypass security controls; in reality, these APIs require proper authentication and authorization. Misunderstanding these points can lead to selecting incorrect answers that describe physical or protocol-related concepts rather than software interfaces.

Why the other options are wrong

B

This option incorrectly describes a northbound API as a cable type, which is a physical concept unrelated to the logical API direction in controller architectures.

C

This option confuses northbound APIs with routing protocols like link-state protocols, which are unrelated to the software interface role of northbound APIs.

D

This option falsely claims that northbound APIs remove the need for authentication, ignoring that security controls remain essential for API access.

When would these options actually be correct?

B

If the question were about the physical infrastructure of a network and asked about the types of cables used for interconnecting network devices, then option B could be correct in that context, specifically referring to a type of cable like fiber optic or Ethernet used between controller clusters.

C

If the question were to ask about the protocols used by a controller to communicate with switches, specifically focusing on network topology and routing, then option C could be correct as it would refer to the protocols that maintain network state information.

D

In a question asking about security features of a network controller, if it specifically states that the controller's design includes a feature that eliminates the need for authentication for certain operations, then option D could be correct.

Why candidates pick the wrong answer

B

Candidates may be tempted by option B due to familiarity with networking concepts, where cables are often discussed in the context of connectivity, leading to confusion about the terminology used in API discussions.

C

Candidates may find option C tempting due to the association of 'northbound' with network communication, leading them to mistakenly connect it with the protocols that facilitate controller-switch interactions, rather than understanding the API's role.

D

Candidates may find this option tempting because they might associate APIs with security features and assume that a simplified authentication process could be a benefit of a northbound API.

1275
MCQhard

A subnet requires 200 usable host addresses. Which prefix is the smallest that meets the requirement?

A./25
B./24
C./26
D./27
AnswerB

A /24 prefix allocates 8 bits for host addressing, producing 2^8 = 256 total addresses. After deducting the network and broadcast addresses, 254 usable host addresses remain, which comfortably exceeds the required 200. This makes /24 the correct prefix, as it is the smallest one that meets the requirement.

Why this answer

A /24 is the smallest valid choice. In plain language, the subnet needs enough total addresses so that after the network and broadcast addresses are reserved, 200 hosts still remain. A /25 is too small because it provides only 126 usable hosts. A /24 provides 254 usable hosts, which satisfies the requirement while being the next logical prefix size up.

This is a standard host-capacity planning question. The key is to work from usable hosts, not just total addresses, and then choose the smallest prefix that actually works.

Exam trap

Ensure you calculate usable addresses, not just total addresses, and choose the smallest prefix that meets the requirement.

Why the other options are wrong

A

A /25 subnet provides 126 usable host addresses, which is insufficient for a requirement of 200 usable addresses. Therefore, it does not meet the specified needs of the question.

C

A /26 subnet provides only 62 usable host addresses (64 total minus 2 for network and broadcast), which is insufficient for the requirement of 200 usable addresses.

D

Option D: /27 provides only 30 usable host addresses (32 total addresses minus 2 for network and broadcast), which is insufficient for the requirement of 200 usable host addresses.

When would these options actually be correct?

A

If the question required a subnet that accommodates up to 126 usable host addresses, such as needing to support a small department within a larger organization, then /25 would be the correct answer.

C

If the question specified a requirement for a maximum of 62 usable host addresses, then a /26 subnet would be the correct choice, as it meets that specific need.

D

In a different scenario where a question asks for the smallest subnet that can accommodate up to 30 hosts, option D: /27 would be correct, as it provides exactly 30 usable addresses, meeting the requirement.

Why candidates pick the wrong answer

A

Candidates might choose /25 due to a misunderstanding of subnetting calculations, mistakenly believing that it offers enough addresses for larger networks or confusing it with the next larger prefix, /24.

C

Candidates may choose /26 due to a misunderstanding of subnetting, thinking that smaller prefixes can still accommodate a larger number of hosts, or they may confuse the number of hosts with the prefix length.

D

Candidates may choose option D due to a misunderstanding of subnetting, thinking that smaller prefixes can still meet the host requirements, or they may confuse the number of usable addresses with the total address count.

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