CCNA Network Services Security Questions — Page 7 of 7

451

Multi-Selectmedium

A branch router is acting as a DHCP server. Which two parameters can it provide directly to clients through DHCP?

Select 2 answers

A.Default gateway

B.DNS server address

C.OSPF area number

D.Switch port duplex setting

E.STP root bridge priority

AnswersA, B

This is usually supplied with the router option.

Why this answer

DHCP (Dynamic Host Configuration Protocol) is designed to automatically assign IP configuration parameters to clients. The default gateway (option 3) and DNS server address (option 6) are standard DHCP options defined in RFC 2132, which a router acting as a DHCP server can directly provide to clients to enable network connectivity and name resolution.

Exam trap

Cisco often tests the distinction between DHCP-provided parameters (Layer 3/4) and switch-specific or routing protocol parameters (Layer 2/3), leading candidates to mistakenly select options like OSPF area or STP priority that are not DHCP options.

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452

MCQhard

An administrator needs to configure an ACL to block HTTP traffic from subnet 10.10.10.0/24 to the web server at 172.16.1.10 while permitting all other traffic. Which ACL entry should be placed first?

A.deny tcp 10.10.10.0 0.0.0.255 host 172.16.1.10 eq 80

B.deny ip 10.10.10.0 0.0.0.255 host 172.16.1.10

C.permit tcp 10.10.10.0 0.0.0.255 host 172.16.1.10 eq 80

D.deny udp 10.10.10.0 0.0.0.255 host 172.16.1.10 eq 80

AnswerA

This is correct because it blocks only HTTP traffic from the specified subnet to the specific server.

Why this answer

The ACL needs a narrow deny statement that matches only TCP port 80 from the specified source subnet to the specific server. In practical terms, the requirement is not to block all IP traffic or all access to the host. It is to stop normal HTTP while allowing everything else. That means the entry must be precise.

This is the kind of ACL question the CCNA exam likes because it forces you to distinguish protocol, destination, and service rather than relying on vague source-only logic.

Exam trap

Be careful to distinguish between blocking all traffic and blocking specific services. Ensure you understand the requirement to block only HTTP traffic, not all IP traffic.

Why the other options are wrong

Option B is incorrect because it denies all IP traffic from the specified source to the destination, which is broader than required and does not specifically target HTTP traffic on port 80.

Option C is incorrect because it permits HTTP traffic from the specified source to the web server, which is contrary to the requirement to block this traffic. The question specifically asks for a rule that denies HTTP access.

Option D is incorrect because it specifies 'deny udp', which does not block HTTP traffic, as HTTP uses TCP, not UDP. Therefore, it fails to meet the requirement of blocking HTTP from the specified source to the web server.

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453

MCQhard

An administrator wants to prevent a specific subnet from using Telnet to reach network devices, while still allowing SSH from that same subnet. What is the strongest reason a standard ACL is not enough by itself?

A.Because the policy must distinguish Telnet from SSH, which requires protocol or port-level matching.

B.Because standard ACLs are valid only on wireless networks.

C.Because Telnet and SSH always use the same destination port.

D.Because SSH can never be filtered with ACLs.

AnswerA

This is correct because source-only matching cannot separate those two protocols.

Why this answer

A standard ACL is not enough by itself because the policy depends on distinguishing different protocols or destination ports, not just source address. In practical terms, the source subnet is the same for both Telnet and SSH. The ACL therefore needs to tell those two management protocols apart, which requires more granular matching than source-only logic.

This is one of the clearest examples of why extended ACL capability matters.

Exam trap

Do not confuse the capabilities of standard ACLs with those of extended ACLs. Remember, standard ACLs filter only by source IP.

Why the other options are wrong

Standard ACLs are not limited to wireless networks; they can be applied to any interface on a router, including wired connections. This option misrepresents the applicability of standard ACLs.

This option is incorrect because Telnet and SSH use different destination ports; Telnet typically uses port 23, while SSH uses port 22, allowing for distinct filtering in ACLs.

This option is incorrect because SSH can indeed be filtered using ACLs, as they can match traffic based on IP addresses and protocols. Standard ACLs can be applied to control SSH traffic just like any other traffic type.

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454

MCQhard

Which NAT design is most appropriate when many inside users need outbound Internet access through one public IPv4 address, but no inbound server publishing is required?

A.PAT overload

B.Static NAT for every host

C.No NAT, because private IPv4 addresses are Internet-routable

D.DHCP relay

AnswerA

This is correct because PAT allows many inside sessions to share one public address by using ports.

Why this answer

The most appropriate design is PAT overload. In practical terms, many internal users can share one public IPv4 address because PAT distinguishes their sessions using transport-layer ports. This is the most common solution when the requirement is outbound access for many clients rather than predictable inbound access to a specific internal server.

Static NAT would be the wrong design here because it creates fixed one-to-one mappings and consumes more public address space than needed for this use case. PAT is specifically built for many-to-one outbound translation.

Exam trap

A frequent exam trap is selecting static NAT or no NAT for outbound Internet access when many internal users share one public IP. Static NAT creates one-to-one mappings, consuming excessive public IP addresses unnecessarily. Choosing no NAT assumes private IPv4 addresses are routable on the Internet, which is false.

Another trap is confusing DHCP relay with NAT; DHCP relay only forwards DHCP messages and does not perform address translation. Candidates must recognize that PAT overload is the correct design for many-to-one outbound translation without inbound server publishing, avoiding these common misconceptions.

Why the other options are wrong

Static NAT for every host is incorrect because it requires a unique public IP address per internal host, which is inefficient and unnecessary when only outbound access is needed without inbound server publishing.

No NAT is incorrect because private IPv4 addresses are not routable on the public Internet and must be translated to public addresses to communicate externally.

DHCP relay is incorrect because it only forwards DHCP messages between clients and servers and does not perform any IP address translation or NAT functions.

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455

MCQhard

A switch shows a clock that is several minutes off from other devices even though an NTP server has been configured. Which issue is the most likely cause?

A.The NTP server is unsynchronized or unreachable

B.The device must run Syslog before NTP can sync

C.NTP requires a trunk port on the management VLAN

D.The clock can sync only if DNS is configured

AnswerA

This is correct because NTP requires a reachable, synchronized time source. If the server is unreachable or not synchronized, the switch cannot update its clock, leading to drift.

Why this answer

NTP requires IP reachability to the time source. If the NTP server is unreachable due to routing or ACL issues, the switch falls back to its local clock, causing drift. Option A is correct.

Option B is wrong because Syslog has no effect on NTP synchronization. Option C is incorrect because NTP does not require a trunk port; it can operate over any VLAN with IP connectivity. Option D is false because DNS is only needed if the NTP server is specified by hostname; the server can be reached by IP address without DNS.

Exam trap

A common mistake is thinking that unrelated services like Syslog, trunk ports, or DNS are prerequisites for NTP; only IP connectivity to a synchronized NTP server matters.

Why the other options are wrong

Syslog and NTP are independent protocols; Syslog does not need to run before NTP can synchronize.

NTP works over any IP network; there is no requirement for a trunk port on the management VLAN.

DNS is only needed if the NTP server is referenced by hostname rather than IP address; many configurations use IP addresses directly.

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456

MCQmedium

Users on a new access switch can reach devices in their own VLAN but cannot reach the default gateway on the distribution switch. Based on the exhibit, what is the most likely cause?

A.VLAN 30 is missing from the allowed VLAN list on the trunk.

B.The user ports should be configured as trunks.

C.The SVI for VLAN 30 must be shutdown for inter-VLAN routing to work.

D.The trunk native VLAN must be changed to VLAN 30.

AnswerA

That prevents VLAN 30 frames from reaching the distribution switch.

Why this answer

The trunk allows only VLANs 10 and 20, so VLAN 30 traffic never crosses the uplink. Local switching inside VLAN 30 on the access switch can still work, which is why same-VLAN communication succeeds. Adding VLAN 30 to the allowed list is the direct fix.

Exam trap

A common exam trap is assuming that user ports must be trunks to enable VLAN communication beyond the local switch. In reality, user ports should remain access ports assigned to a single VLAN. Another trap is thinking that the SVI for VLAN 30 must be shut down to fix routing issues, but an active SVI is necessary for inter-VLAN routing.

Additionally, candidates may incorrectly focus on native VLAN mismatches, which do not block VLAN 30 traffic if the VLAN is not allowed on the trunk. The real issue is the missing VLAN 30 in the trunk's allowed VLAN list, which prevents VLAN 30 frames from reaching the distribution switch and the default gateway.

Why the other options are wrong

Incorrect because user ports should be configured as access ports, not trunks. Configuring user ports as trunks is unnecessary and can cause security and connectivity issues.

Incorrect because the SVI for VLAN 30 must be active for inter-VLAN routing to function. Shutting down the SVI would prevent routing, not enable it.

Incorrect because changing the trunk native VLAN to VLAN 30 is unrelated to the problem. Native VLAN mismatches affect untagged traffic but do not block VLAN 30 tagged frames if the VLAN is allowed.

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457

MCQhard

An engineer wants remote administrative access to remain available but also wants session contents protected in transit. Which management choice best supports that goal?

A.SSH

B.Telnet

C.Open wireless access

D.Native VLAN 1

AnswerA

This is correct because SSH supports encrypted remote administration.

Why this answer

The best choice is SSH because it provides encrypted remote administrative access. In plain language, the engineer wants administrators to keep managing devices remotely, but without exposing credentials or session contents in clear text. SSH solves that by protecting the traffic in transit, which is why it is preferred over older plaintext protocols such as Telnet.

This is a core management-plane security principle. The goal is not to remove remote administration, but to perform it safely. The correct answer is the one that aligns with secure remote access rather than convenience at the expense of protection.

Exam trap

A common exam trap is selecting Telnet because it allows remote access, ignoring that it transmits data in clear text. This mistake overlooks the critical security requirement to protect session contents during transit. Another trap is choosing options unrelated to encryption, such as native VLAN or open wireless access, which do not address secure remote management.

Candidates must focus on protocols that provide confidentiality and integrity for administrative sessions, not just connectivity.

Why the other options are wrong

Telnet is incorrect because it transmits data in clear text, exposing sensitive information to attackers and failing to protect session contents during transit.

Open wireless access is unrelated to secure remote management; it does not provide encryption or protect administrative sessions, making it irrelevant to the question.

Native VLAN 1 configuration does not affect encryption or security of remote management protocols, so it does not support the goal of protecting session contents.

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458

MCQhard

A network engineer notices that internal hosts (192.168.1.0/24) can reach external servers on the internet, but replies from external servers never reach the internal hosts. The router R1 is configured with dynamic NAT to translate the internal subnet to a pool of public IPs (203.0.113.10-203.0.113.20). The engineer runs 'show ip nat translations' and sees only a few stale translations. What is the most likely cause of the issue?

A.The access list 'NAT' is incorrect; it should permit only specific hosts, not the entire subnet.

B.The outside interface (GigabitEthernet0/0) is missing the 'ip nat outside' command.

C.The NAT configuration lacks the 'overload' keyword, so the pool is exhausted quickly.

D.The NAT pool 'POOL' has too few addresses; it should be expanded to a /24 subnet.

AnswerB

Without 'ip nat outside' on the outside interface, the router does not translate return packets from the outside to the inside. Adding this command enables NAT to work bidirectionally.

Why this answer

The correct answer is B because the 'ip nat outside' command must be applied to the interface facing the external network (GigabitEthernet0/0) for the router to translate return traffic. Without it, the router does not perform NAT on packets arriving on that interface, so replies from external servers are forwarded without translation back to the inside local IPs, which are not routable on the internet. The stale translations indicate that outbound translations were created but never used for return traffic, confirming the missing outside interface command.

Exam trap

Cisco often tests the requirement that both 'ip nat inside' and 'ip nat outside' must be configured on the respective interfaces for NAT to work bidirectionally, and the trap here is that candidates assume only the inside interface needs the command or confuse the symptom with pool exhaustion or ACL issues.

Why the other options are wrong

The access list correctly matches the internal subnet, so this is not the root cause.

Even without overload, dynamic NAT should work for the first 11 hosts; the problem is that return packets are not being translated.

The pool size is not the issue; the router is not translating return traffic due to missing 'ip nat outside'.

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459

MCQhard

A network administrator configures PAT on a router to allow internal hosts in the 10.10.10.0/24 subnet to access the Internet. Afterward, users report that they can ping public IP addresses but cannot access any websites. The administrator verifies that the access list for NAT matches the correct subnet, and the 'ip nat inside source list 1 interface GigabitEthernet0/1 overload' command is applied. What is the most likely cause of this issue?

A.The router's DNS proxy is misconfigured, preventing resolution of website names.

B.The PAT translation table is full, causing new TCP connection requests to be dropped.

C.The 'overload' keyword was omitted, causing the router to use dynamic NAT with a single-address pool.

D.A static NAT entry for a web server is using the same public IP address as the PAT overload.

AnswerB

PAT uses source port translation to map many internal addresses to a single public IP. ICMP (ping) does not consume a port mapping and can still be translated even when the table is exhausted. New TCP connections, required for web traffic, will fail when no free source port is available.

Why this answer

The ability to ping public IP addresses confirms that IP routing and PAT translation are working for ICMP traffic. However, the failure to access websites (HTTP/HTTPS) while ping succeeds indicates that the PAT translation table is likely exhausted, preventing the router from creating new translations for TCP connections. The 'overload' keyword is correctly configured, so the issue is not a missing keyword but rather resource exhaustion in the NAT table.

Exam trap

Cisco often tests the distinction between ICMP and TCP behavior under PAT exhaustion—candidates assume that if ping works, all IP connectivity is fine, but the trap is that PAT table exhaustion selectively drops new TCP sessions while allowing existing or low-volume ICMP traffic.

Why the other options are wrong

The scenario explicitly mentions successful pings to IP addresses, so name resolution is not the cause.

The command output explicitly shows 'overload', and the symptom (ping works, TCP fails) is inconsistent with a missing overload keyword.

A static NAT conflict would affect all traffic (including ICMP), not just web traffic.

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460

MCQmedium

Why is multifactor authentication generally stronger than password-only access?

A.It removes the need for authorization policies.

B.It relies on more than one authentication factor.

C.It guarantees that credentials can never be phished.

D.It replaces encryption on the network.

AnswerB

Correct. That is the core strength of MFA.

Why this answer

MFA combines independent factors, so compromise of one factor does not automatically grant access.

Exam trap

A common exam trap is selecting options that overstate MFA’s capabilities, such as assuming it guarantees immunity to phishing or replaces encryption. MFA reduces risk but does not eliminate all attack vectors, and it does not substitute for encryption protocols that protect data in transit. Another trap is confusing authentication with authorization; MFA strengthens authentication but does not remove the need for proper authorization policies.

Recognizing these distinctions is critical to avoid incorrect answers that exaggerate MFA’s role or misunderstand its function in network security.

Why the other options are wrong

Option A is incorrect because multifactor authentication strengthens authentication processes but does not remove the need for authorization policies. Authorization controls determine what an authenticated user can access, which remains essential regardless of the authentication method.

Option C is incorrect because while MFA reduces the risk of phishing attacks by requiring multiple factors, it does not guarantee that credentials can never be phished. Attackers may still find ways to bypass or trick users into revealing multiple factors.

Option D is incorrect because authentication methods like MFA do not replace encryption on the network. Encryption protects data confidentiality and integrity during transmission, which is a separate security function from verifying user identity.

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461

MCQeasy

Which NAT feature allows many inside hosts to share one public IPv4 address by using unique source port numbers?

A.Static NAT

B.PAT

C.NTP authentication

D.Port security

AnswerB

PAT uses port numbers to multiplex many inside devices to one or a few public addresses.

Why this answer

PAT, sometimes called NAT overload, keeps track of connections by using Layer 4 port numbers so many private hosts can share a single public address.

Exam trap

A common exam trap is mistaking Static NAT for PAT. Static NAT creates a fixed one-to-one mapping between inside and outside IP addresses without using port numbers, so it cannot support multiple hosts sharing one public IP. Another trap is confusing unrelated features like NTP authentication or port security with NAT functions.

NTP authentication secures time synchronization and port security restricts MAC addresses on switch ports; neither involves IP address translation or port multiplexing. Candidates who overlook the role of Layer 4 port numbers in PAT may incorrectly select these options, missing the key concept that PAT uniquely identifies sessions by port numbers to allow many hosts to share a single public IPv4 address.

Why the other options are wrong

Static NAT provides a fixed one-to-one mapping between private and public IP addresses. It does not use port numbers to allow multiple inside hosts to share a single public IP, so it cannot fulfill the requirement of the question.

NTP authentication secures Network Time Protocol messages and is unrelated to address translation or NAT. It does not allow multiple hosts to share a public IP address.

Port security controls which MAC addresses can access a switch port to enhance Layer 2 security. It does not perform IP address translation or use port numbers to share public IP addresses.

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462

Matchingmedium

Match each NAT term to its most accurate description.

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

Concepts

Matches

Private address used by the host on the internal network

Address that represents the internal host to outside networks

Fixed one-to-one translation

Many-to-one translation using ports

Why these pairings

NAT terms describe address perspectives: Inside Local is the internal host's IP, Inside Global is its external IP, Outside Local is the external host's IP seen internally, Outside Global is its actual external IP, Static NAT provides permanent mapping, and Dynamic NAT uses a pool.

Exam trap

The exam trap is confusing the perspective (inside vs. outside) and the location (local vs. global). Remember: 'Local' is the address as seen from the inside network, 'Global' is the address as seen from the outside network.

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463

Multi-Selectmedium

Which two features commonly strengthen access-switch security for user-facing ports? (Choose two.)

Select 2 answers

A.Port security

B.BPDU Guard

C.Administrative distance

D.Route summarization

AnswersA, B

Correct. It helps control which MAC addresses may appear on a port.

Why this answer

Port security can limit learned MAC addresses, and BPDU Guard can shut down an edge port that unexpectedly receives BPDUs.

Exam trap

A common exam trap is selecting administrative distance or route summarization as security features for user-facing access ports. Administrative distance is a routing protocol metric used to select the best path and has no role in access-switch port security. Similarly, route summarization is a routing optimization technique that reduces routing table size but does not affect port security.

Candidates may confuse these routing concepts with security features due to their importance in network design, but they do not strengthen access-switch security for user-facing ports. Recognizing this distinction is critical to avoid losing points on this question.

Why the other options are wrong

Administrative distance is a routing protocol metric used to select the best path and does not relate to access-switch port security. It does not control port access or prevent unauthorized devices, so option C is incorrect.

Route summarization is a routing optimization technique that reduces routing table size and update traffic. It does not provide any security controls for user-facing switch ports, so option D is incorrect.

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464

MCQhard

A monitoring system already collects Syslog and SNMP data. The network team now wants visibility into which applications or host conversations are driving link utilization. What is the strongest addition?

A.NetFlow

B.Another SSID

C.PortFast

D.A larger wildcard mask

AnswerA

This is correct because NetFlow provides detailed flow-level visibility into traffic usage.

Why this answer

The strongest addition is NetFlow because it provides traffic-flow visibility. In practical terms, Syslog and SNMP are useful, but they do not directly answer detailed conversation-level questions such as which hosts, protocols, or flows are consuming the most bandwidth. NetFlow is designed to answer exactly that kind of question.

This is about choosing the right operational tool for the visibility gap.

Exam trap

A frequent exam trap is selecting options like PortFast or adding another SSID, which are unrelated to traffic flow monitoring. PortFast is an STP feature that speeds up port transitions but does not provide any insight into bandwidth usage or application-level traffic. Similarly, adding another SSID only affects wireless network segmentation and does not offer visibility into which hosts or applications consume bandwidth.

Another trap is thinking that changing ACL wildcard masks can help analyze traffic flows, but ACLs only filter traffic and do not provide analytics. Recognizing that only NetFlow delivers detailed flow-level data prevents these common mistakes.

Why the other options are wrong

Adding another SSID is incorrect because it only creates a new wireless network segment and does not provide any traffic flow or bandwidth usage information. It does not help identify which applications or hosts are using the link.

PortFast is an STP feature that speeds up port transitions on edge ports but does not monitor or analyze traffic flows. It has no relevance to identifying bandwidth usage or application-level visibility.

Using a larger wildcard mask in ACLs affects traffic filtering rules but does not provide analytics or visibility into traffic flows. ACLs do not report on bandwidth consumption or application usage.

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465

Multi-Selectmedium

Which two statements accurately describe DHCP?

Select 2 answers

A.It can automatically provide an IP address to a client.

B.It can provide additional configuration such as default gateway and DNS server information.

C.It resolves hostnames into IP addresses.

D.It elects the designated router in OSPF.

E.It replaces the need for subnet masks.

AnswersA, B

This is correct because address assignment is a core DHCP function.

Why this answer

DHCP is used to provide IP configuration automatically to hosts. In practical terms, it can supply an IP address, subnet mask, default gateway, and often DNS server information. This reduces manual effort and helps standardize endpoint configuration across a network.

The wrong answers often confuse DHCP with DNS or routing. The two correct answers are the ones focused on automatic host configuration.

Exam trap

A common exam trap is confusing DHCP with DNS or routing protocol functions. Some candidates mistakenly believe DHCP resolves hostnames to IP addresses, but this is the role of DNS. Others incorrectly think DHCP participates in routing protocol processes such as OSPF designated router elections, which it does not.

Additionally, some may assume DHCP eliminates the need for subnet masks, but DHCP actually provides subnet mask information to clients. Recognizing that DHCP strictly handles IP address and related configuration assignment prevents these errors.

Why the other options are wrong

Incorrect. DHCP does not resolve hostnames to IP addresses; this is the responsibility of DNS, a separate IP service.

Incorrect. DHCP does not participate in routing protocol operations like OSPF designated router election, which is a function of OSPF itself.

Incorrect. DHCP supplies subnet masks to clients but does not replace the need for subnet masks; subnetting remains a fundamental network design concept.

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466

MCQmedium

As a general rule, where should an extended ACL be placed?

A.As close to the source as practical

B.As close to the destination as possible in all cases

C.Only on the default gateway

D.Only on WAN interfaces

AnswerA

Correct. This is the common placement guideline.

Why this answer

Extended ACLs are commonly placed near the source to stop unwanted traffic earlier and conserve bandwidth and device resources.

Exam trap

Remember that extended ACLs should be placed near the source, not the destination or core, to effectively manage traffic.

Why the other options are wrong

Placing an extended ACL as close to the destination can lead to unnecessary traffic being processed by intermediate devices, which is inefficient. Extended ACLs are designed to filter traffic based on source and destination, so positioning them closer to the source enhances performance and security.

This option is incorrect because placing an extended ACL only on the default gateway limits its effectiveness in controlling traffic originating from various sources across the network. Extended ACLs should be strategically placed closer to the source to filter traffic before it reaches the destination.

Placing an extended ACL only on WAN interfaces can lead to inefficient traffic filtering, as it may not adequately control traffic originating from internal sources. Extended ACLs should ideally be positioned close to the source to effectively manage traffic before it reaches the destination.

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467

MCQhard

A router is configured for PAT using the WAN interface address. Which command element is most directly associated with allowing many internal users to share that single outside address?

A.overload

B.inside

C.list 1

D.interface

AnswerA

This is correct because `overload` enables PAT behavior using transport-layer ports.

Why this answer

The `overload` element is the critical part. In plain language, that keyword tells the router to perform Port Address Translation so many inside sessions can be represented through the same outside IP address at the same time. Without overload, the router would be performing a different translation behavior and would not achieve the same many-to-one sharing model.

This is one of the most recognizable NAT design terms in CCNA because it directly distinguishes PAT from simple one-to-one translation methods. The correct answer is the part of the configuration that signals multi-session sharing through port tracking.

Exam trap

A common exam trap is selecting options like `inside`, `list 1`, or `interface` as the element that enables multiple internal users to share a single outside address. While these elements are part of the NAT configuration, they do not by themselves enable PAT. The `inside` keyword only marks interfaces as internal, the ACL (`list 1`) defines which addresses are translated, and specifying the `interface` chooses the public IP address source.

However, without the `overload` keyword, the router cannot perform port-based multiplexing, so many-to-one sharing fails. Candidates often overlook that `overload` is the explicit command that activates PAT, making it the correct answer.

Why the other options are wrong

Incorrect. The `inside` keyword only marks an interface as internal for NAT direction but does not enable multiple hosts to share one outside address.

Incorrect. The access list (`list 1`) specifies which internal addresses are translated but does not activate PAT or many-to-one sharing by itself.

Incorrect. Specifying the interface determines the outside IP address used for translation but does not enable PAT without the `overload` keyword.

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468

MCQhard

Exhibit: Users report no internet access after PAT was configured. The inside and outside interfaces are marked correctly. Which missing configuration is the most likely cause?

A.No ACL and nat overload statement identifying inside source addresses

B.No DHCP pool on the outside interface

C.No CDP enabled on the router

D.No syslog server configured

AnswerA

Correct choice.

Why this answer

PAT needs both the inside and outside interface roles and a NAT statement referencing an ACL that identifies the inside local addresses. Without the ACL match and NAT overload rule, translation does not occur for user traffic.

Exam trap

A frequent exam trap is believing that configuring the inside and outside interfaces alone is enough for PAT to function correctly. Candidates may overlook the necessity of an ACL that explicitly identifies the inside local addresses for translation. Without this ACL and the corresponding NAT overload statement, the router cannot perform address translation, causing intermittent or failed internet connectivity.

This mistake often occurs because the interface roles are visible and seem sufficient, but the translation logic depends on the ACL match. Understanding that PAT requires both interface roles and an ACL-based NAT overload rule is critical to avoid this pitfall.

Why the other options are wrong

Incorrect. DHCP pools assign IP addresses to clients and are unrelated to NAT or PAT configuration. Lack of a DHCP pool on the outside interface does not affect PAT functionality.

Incorrect. CDP is a Layer 2 protocol used for device discovery and does not influence NAT or PAT operations. Its absence does not cause internet access issues related to PAT.

Incorrect. Syslog servers are used for logging and monitoring router events. Not configuring a syslog server does not impact NAT translation or internet connectivity.

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469

Drag & Dropmedium

Drag and drop the following steps into the correct order to configure and apply an extended IPv4 ACL on a Cisco router to block Telnet traffic from subnet 192.168.1.0/24 to host 10.0.0.1 and permit all other IP traffic.

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

7Step 7

Why this order

Correct order: 1) Identify the traffic to filter and the interface/direction because this planning determines all subsequent configuration choices. 2) Enter global configuration mode to access ACL definition. 3) Configure the deny statement first — ACLs are processed top-down, so the specific deny must precede the general permit to actually block the unwanted traffic. 4) Add the permit statement after the deny to allow everything else. 5) Enter interface configuration mode to attach the ACL to a specific port. 6) Apply the ACL with the correct direction (inbound) using the ip access-group command, which activates the filtering. 7) Verify the ACL is correctly applied to confirm the configuration is functioning as intended.

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470

MCQhard

A company wants internal users to share one public IPv4 address for outbound Internet access, while keeping sessions separate. Which NAT approach best meets that requirement?

A.PAT overload

B.Static NAT only

C.No NAT, because private IPv4 addresses are Internet-routable

D.DHCP relay

AnswerA

This is correct because PAT uses port values to let many internal sessions share one public IPv4 address.

Why this answer

PAT is the correct approach because it allows many internal sessions to share one outside IPv4 address while distinguishing them by port numbers. In plain language, PAT gives the office an efficient many-to-one translation model that works well for ordinary user Internet access when public addresses are limited.

This is different from static NAT, which gives a fixed one-to-one mapping, and from dynamic NAT pools that usually rely on multiple public addresses. The correct answer is the translation method designed specifically for shared public-address use across many sessions.

Exam trap

A common exam trap is selecting static NAT as the solution because it involves address translation, but static NAT only supports one-to-one mappings and cannot handle multiple internal users sharing a single public IP address. Another frequent mistake is assuming private IPv4 addresses can be routed on the Internet without NAT, which is incorrect because private addresses are non-routable externally. Additionally, confusing DHCP relay with NAT functions can mislead candidates, as DHCP relay only forwards DHCP messages and does not perform address translation.

Recognizing that PAT overload uniquely enables many-to-one translation with port differentiation is crucial to avoid these pitfalls.

Why the other options are wrong

Static NAT only provides a one-to-one mapping between private and public IP addresses, so it cannot support multiple internal users sharing one public IP address simultaneously, making it unsuitable for the scenario.

No NAT is incorrect because private IPv4 addresses are not routable on the public Internet; without NAT, internal users cannot access external resources using private IPs alone.

DHCP relay is unrelated to NAT or IP address translation; it simply forwards DHCP requests between clients and servers and does not enable sharing of public IP addresses for Internet access.

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471

Drag & Dropmedium

Drag and drop the following steps into the correct order to plan, configure, and apply an extended ACL that denies Telnet from a specific host to a server subnet, 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

The correct sequence is: create the ACL (A), apply it to the interface (B), verify it works (D), then save the configuration (C). This prevents saving a faulty ACL. Verifying after saving (C before D) risks persisting errors and is not the Cisco recommended workflow.

Exam trap

Do not confuse the order of creation and application: you must create the ACL before applying it. Also, always verify before saving to avoid locking in errors.

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472

MCQmedium

A network administrator wants to secure remote CLI access to a Cisco router, moving beyond simple username/password authentication. Which approach best achieves this goal?

A.Use stronger or additional authentication controls to improve remote administrative access security

B.Replace SSH with Telnet to simplify troubleshooting

C.Configure an extended ACL to limit remote access to specific source IP addresses

D.Disable password authentication and rely solely on device location in the network

AnswerA

This is correct because the goal is to improve authentication strength rather than rely only on a weak single factor.

Why this answer

The goal is to strengthen authentication beyond a simple password. Cisco AAA (Authentication, Authorization, and Accounting) using TACACS+ or RADIUS provides stronger, centralized authentication. Secure Shell (SSH) with key-based or two-factor authentication also enhances security.

Option A correctly describes this concept, while the other options either weaken security (B, D) or address access control via ACLs, which does not improve the authentication factor itself (C).

Exam trap

A common trap is thinking that limiting access with an ACL (option C) satisfies the goal, but ACLs restrict source addresses, not strengthen the authentication process. Another trap is confusing stronger authentication with simpler troubleshooting (B) or location-based trust (D).

Why the other options are wrong

Telnet transmits credentials in plaintext, making it less secure than SSH and opposite to the goal of stronger authentication.

An ACL restricts source addresses but does not strengthen the authentication factor itself; it is an authorization control, not an authentication improvement.

Removing password authentication and relying on location removes all credential verification, making the device vulnerable to unauthorized access from permitted locations.

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473

PBQhard

You are connected to R1. The network uses a single router with two subnets: 192.168.1.0/24 (connected to GigabitEthernet0/0) and 10.0.0.0/30 (connected to GigabitEthernet0/1). Configure an extended named ACL called 'FILTER_HTTP' that permits HTTP traffic (TCP port 80) from the 192.168.1.0/24 subnet to any destination, and includes an explicit deny statement to deny all other IP traffic. Apply the ACL inbound on GigabitEthernet0/0. Then verify that HTTP traffic is allowed and all other traffic is blocked.

Network Topology

Hints

•Remember the implicit deny at the end of every ACL – you may not need an explicit deny, but the question asks to deny all other IP traffic.
•Use the correct wildcard mask for the subnet 192.168.1.0/24: 0.0.0.255.
•Apply the ACL to the interface that receives traffic from the internal subnet.

A.ip access-list extended FILTER_HTTP permit tcp 192.168.1.0 0.0.0.255 any eq 80 deny ip any any interface GigabitEthernet0/0 ip access-group FILTER_HTTP in

B.access-list 100 permit tcp 192.168.1.0 0.0.0.255 any eq 80 access-list 100 deny ip any any interface GigabitEthernet0/0 ip access-group 100 in

C.ip access-list extended FILTER_HTTP permit tcp 192.168.1.0 0.0.0.255 any eq 80 interface GigabitEthernet0/0 ip access-group FILTER_HTTP in

D.ip access-list extended FILTER_HTTP permit tcp 192.168.1.0 0.0.0.255 any eq 80 deny ip any any interface GigabitEthernet0/1 ip access-group FILTER_HTTP in

AnswerA

solution

! R1
ip access-list extended FILTER_HTTP
permit tcp 192.168.1.0 0.0.0.255 any eq 80
deny ip any any
interface GigabitEthernet0/0
ip access-group FILTER_HTTP in

Why this answer

The task requires creating an extended named ACL 'FILTER_HTTP' that permits TCP port 80 from source 192.168.1.0/24 to any destination, and then denies all other IP traffic (the implicit deny will block everything else, but you must explicitly add a deny ip any any statement to make the intent clear). The ACL must be applied inbound on GigabitEthernet0/0. The solution uses the commands: ip access-list extended FILTER_HTTP, permit tcp 192.168.1.0 0.0.0.255 any eq 80, deny ip any any, and interface GigabitEthernet0/0, ip access-group FILTER_HTTP in.

Verification with show access-lists and show ip interface GigabitEthernet0/0 confirms the ACL and its application.

Exam trap

Pay attention to the requirement for a named ACL versus numbered ACL. Also, note that while the implicit deny exists, the question explicitly asks for a deny statement, so you must include it. Finally, ensure the ACL is applied to the correct interface and direction.

Why the other options are wrong

The specific factual error is that the ACL must be named 'FILTER_HTTP', but this option uses a numbered ACL (100).

The specific factual error is that the ACL does not include an explicit deny ip any any, which is needed to satisfy the requirement of denying all other IP traffic.

The specific factual error is that the ACL is applied to the wrong interface (GigabitEthernet0/1 instead of GigabitEthernet0/0).

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474

MCQhard

Based on the exhibit, why is the ACL blocking more traffic than intended?

A.Because the ACL denies all TCP traffic to the server instead of only Telnet.

B.Because Telnet uses UDP, not TCP.

C.Because the ACL should be a standard ACL, not an extended ACL.

D.Because the host keyword can never be used with TCP statements.

AnswerA

This is correct because the entry lacks the Telnet destination port qualifier and therefore matches too broadly.

Why this answer

The ACL is blocking more traffic than intended because it uses a broad deny against all TCP traffic to the server instead of only the one service that should be denied. In practical terms, the requirement is narrow, but the configured entry is much wider. As a result, multiple TCP-based applications to that server are blocked, not just the intended one.

This is a classic precision problem in ACL design. It tests whether you can compare what the business requirement says against what the ACL actually matches.

Exam trap

The exam trap here is assuming that denying TCP traffic to a server without specifying the Telnet port will only block Telnet sessions. In reality, the ACL entry without the destination port qualifier matches all TCP traffic to that server, blocking multiple services unintentionally. This mistake often arises from confusing standard ACLs, which filter only by source IP, with extended ACLs that require explicit port numbers for service-specific filtering.

Candidates may overlook the need for the 'eq 23' qualifier for Telnet, leading to broader traffic denial and failing the question.

Why the other options are wrong

This option is incorrect because Telnet uses TCP as its transport protocol, not UDP. Therefore, denying TCP traffic is relevant for blocking Telnet, and the statement about UDP is factually wrong.

This option is incorrect because standard ACLs filter only by source IP address and cannot filter by protocol or port. The question requires filtering by service (Telnet), which necessitates an extended ACL, making this option invalid.

This option is incorrect because the 'host' keyword is valid in extended ACLs and is commonly used to specify a single IP address for precise matching. There is no restriction against using 'host' with TCP statements.

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475

MCQmedium

Exhibit: An engineer wants a device to send only warning messages and more critical events to a syslog server. Which logging level should be configured?

A.logging trap debugging

B.logging trap warnings

C.logging trap notifications

D.logging trap informational

AnswerB

Warnings include warning and all more severe levels.

Why this answer

Syslog severity levels include lower numbers for more severe events. Warning is level 4, so setting logging trap warnings sends level 4, 3, 2, 1, and 0 messages.

Exam trap

A frequent exam trap is selecting 'logging trap debugging' or 'informational' because these options seem to provide comprehensive logging. However, these levels include all messages, even low-priority informational and debug messages, which can overwhelm the syslog server and make it difficult to identify critical issues. Another trap is misunderstanding the syslog severity numbering, assuming higher numbers mean higher severity, when in fact, lower numbers indicate more critical events.

This confusion leads to incorrect trap level configuration and ineffective monitoring.

Why the other options are wrong

The option 'logging trap debugging' sets the trap level to 7, which includes all syslog messages from debugging (least severe) up to emergencies (most severe). This floods the syslog server with excessive data, beyond just warnings and critical events, making it unsuitable for the requirement.

The option 'logging trap notifications' sets the trap level to 5, which includes notifications and all more severe messages. However, notifications are less severe than warnings, so this setting would include informational messages that are not requested, making it incorrect.

The option 'logging trap informational' sets the trap level to 6, which includes informational messages and all more severe messages. This level is less severe than warnings and includes many more messages than requested, so it does not meet the requirement.

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476

Multi-Selectmedium

Which two statements accurately describe the value of source restriction on administrative access?

Select 2 answers

A.It reduces the set of network locations from which administrative access is allowed.

B.It can make access monitoring and filtering easier to manage.

C.It removes the need for SSH or other secure transports.

D.It makes logging unnecessary.

E.It can be used only for wireless management.

AnswersA, B

This is correct because source restriction narrows exposure.

Why this answer

Source restriction improves security by reducing the number of places from which administrative traffic is expected and permitted. In practical terms, this makes exposure smaller and monitoring clearer. It does not replace secure protocols or identity controls, but it strengthens the overall design.

This is a layered-management-security question because it emphasizes how source restriction complements other controls.

Exam trap

A common exam trap is to believe that source restriction removes the need for secure transport protocols like SSH or makes logging unnecessary. Some candidates mistakenly think that limiting source IP addresses alone fully secures administrative access. However, source restriction only controls where connections can originate; it does not encrypt data or authenticate users.

Ignoring secure protocols or logging can leave management sessions vulnerable to interception or unauthorized use. The exam tests understanding that source restriction is a complementary control, not a replacement for transport security or auditing.

Why the other options are wrong

Incorrect because source restriction does not replace the need for secure transport protocols like SSH; encryption and authentication remain essential for secure management.

Incorrect because logging is still necessary to maintain visibility and audit trails of administrative access attempts, even when source restriction is applied.

Incorrect because source restriction is not limited to wireless management; it applies broadly to all administrative access methods on Cisco devices.

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477

MCQhard

A network administrator notices that syslog messages from a core router are arriving at the syslog server with timestamps that are hours behind other devices. The router’s NetFlow exports also show incorrect start and end times for flows, making traffic analysis unreliable. The administrator verifies that all router interfaces are up and that the SNMP community strings on the router match the NMS.

A.The logging trap level is set to informational, so only high-severity messages are sent with correct timestamps.

B.The router’s NTP client is configured with an incorrect authentication key.

C.The SNMP v3 user’s privacy password is incorrect, causing the NMS to reject syslog traps.

D.The IP flow cache timeout is set too low, causing NetFlow timestamps to appear skewed.

AnswerB

NTP can use authentication keys to verify server identity. If the client key does not match the server’s key, the router will not trust the time updates and will fail to synchronize. This leaves the router’s clock uncorrected, causing incorrect timestamps in syslog and NetFlow records.

Why this answer

The router's timestamps are incorrect for both syslog messages and NetFlow exports, which points to a system-wide time synchronization issue. NTP (Network Time Protocol) is responsible for maintaining accurate time on network devices, and if the NTP client is configured with an incorrect authentication key, it will fail to synchronize with the NTP server, causing the router's clock to drift. This explains why all time-stamped data (syslog and NetFlow) is consistently behind.

Exam trap

Cisco often tests the distinction between time synchronization issues (NTP) and logging/SNMP configuration issues, so candidates may incorrectly attribute timestamp problems to syslog or SNMP settings rather than the underlying system clock.

Why the other options are wrong

Logging trap level controls which severity messages are forwarded, not the accuracy of the timestamps.

SNMP v3 misconfiguration impacts SNMP traps, not syslog messages, which are sent independently via a different transport.

Cache timeout affects flow export frequency, not the accuracy of the timestamps inside the flow data.

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478

MCQmedium

Why does DNS make networks easier for people to use?

A.It lets people use memorable names instead of raw IP addresses.

B.It assigns IP addresses automatically.

C.It replaces the need for default gateways.

D.It elects the root bridge for STP.

AnswerA

This is correct because name-based access is the main usability benefit of DNS.

Why this answer

DNS makes networks easier to use because it lets people work with names instead of memorizing numeric IP addresses. In practical terms, users can remember a server name much more easily than a string of numbers. DNS creates that naming layer while the network still uses IP underneath.

This usability benefit is one of the main reasons DNS is so important in everyday network operations.

Exam trap

A frequent exam trap is mistaking DNS for DHCP or routing functions. Some candidates incorrectly believe DNS assigns IP addresses automatically, which is actually the role of DHCP. Others think DNS replaces default gateways or participates in spanning-tree protocol (STP) operations, which it does not.

This confusion arises because DNS, DHCP, routing, and STP are all fundamental network services but serve distinct purposes. Misunderstanding these roles can lead to selecting incorrect answers that sound plausible but do not match DNS’s actual function of name resolution.

Why the other options are wrong

Option B is incorrect because DHCP, not DNS, is responsible for automatically assigning IP addresses to devices on a network. DNS only resolves names to IP addresses after assignment.

Option C is incorrect because DNS does not replace default gateways. Default gateways are necessary for routing traffic outside the local subnet, a function unrelated to DNS name resolution.

Option D is incorrect because DNS has no role in Spanning Tree Protocol (STP) operations, including root bridge election, which is a Layer 2 loop prevention mechanism.

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