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CCNA Switching Network Access Questions

75 of 299 questions · Page 2/4 · Switching Network Access topic · Answers revealed

76
Multi-Selectmedium

Which three of the following are correct statements about VLAN configuration and verification on a Cisco switch? (Choose three.)

Select 3 answers
.The 'switchport mode access' command places the interface into a non-trunking mode.
.By default, all ports on a Cisco switch are in VLAN 1.
.The 'show vlan brief' command displays VLANs that are active on the switch.
.VLANs 1002–1005 are reserved for user-created VLANs.
.A VLAN must be manually created before its name can be assigned.
.The 'switchport trunk native vlan' command restricts the native VLAN to only tagged frames.

Why this answer

The correct statements are: (1) The 'switchport mode access' command places the interface into a non-trunking mode; (2) By default, all ports on a Cisco switch are in VLAN 1; (3) The 'show vlan brief' command displays VLANs that are active on the switch. The remaining statements are false because: VLANs 1002–1005 are reserved for legacy FDDI/Token Ring VLANs, not for user-created VLANs; a VLAN does not need to be manually created before its name can be assigned (assigning a port to a new VLAN can automatically create it, after which you can set its name); and the 'switchport trunk native vlan' command does not restrict the native VLAN to only tagged frames—native VLAN traffic is sent untagged.

Exam trap

Candidates often confuse the native VLAN as carrying tagged frames, and mistakenly believe VLANs 1002–1005 are user-configurable, when in fact they are reserved for legacy technologies.

Why the other options are wrong

D

VLANs 1002–1005 are reserved for legacy FDDI and Token Ring, not user-created VLANs.

F

The native VLAN on a trunk sends frames untagged; this command sets the native VLAN, not a tagging restriction.

77
MCQmedium

When spanning tree elects a root bridge, which value is considered first?

A.Lowest MAC address only
B.Lowest bridge priority only
C.Lowest bridge ID, which begins with priority
D.Highest interface bandwidth
AnswerC

In STP, the root bridge is elected by comparing the 8-byte bridge ID (BID), which is formed by a 2-byte priority value followed by the 6-byte MAC address. The lowest BID wins, and because priority occupies the most significant bytes, a switch with a lower priority always beats a switch with a higher priority. Only when priorities are identical does the MAC address become the tiebreaker within the same BID comparison. Thus the actual election value is the full bridge ID, beginning with priority.

Why this answer

The root bridge is the switch with the lowest bridge ID. The bridge ID is made up of priority and MAC address, so priority is considered first, then MAC address if priorities tie.

Exam trap

Remember that the bridge priority is evaluated before the MAC address in the root bridge election process.

Why the other options are wrong

A

The MAC address is only used as a tiebreaker when bridge priorities are equal. It is not the first value considered in root bridge election.

B

The bridge priority is only the first part of the bridge ID; the full bridge ID (priority + MAC address) is compared. If priorities are equal, the MAC address is used as a tiebreaker.

D

Interface bandwidth is used to calculate path cost, which influences port roles (root port, designated port) but does not affect root bridge election. Root bridge election is based solely on bridge ID.

78
PBQmedium

You are connected to SW1 via the console. SW1 is a Layer 2 switch. Ports G0/1 and G0/2 are connected to two PCs that should be in VLAN 10 (Sales). Port G0/3 is a trunk link to another switch. The PCs are currently unable to communicate because the ports are in VLAN 1. Configure the switch to place the ports in the correct VLAN and ensure the trunk is properly configured with 802.1Q encapsulation and native VLAN 99.

Network Topology
trunkPC1SW1 G0/1SW1 G0/2OtherSwitch

Hints

  • Check the current VLAN assignment on access ports.
  • The trunk encapsulation must be set to dot1q for 802.1Q support.
  • Native VLAN should match on both ends of the trunk.
A.Create VLAN 10, assign G0/1 and G0/2 as access ports in VLAN 10, configure G0/3 as trunk with encapsulation dot1q and native VLAN 99.
B.Create VLAN 10, assign G0/1 and G0/2 as access ports in VLAN 10, configure G0/3 as trunk with encapsulation isl and native VLAN 99.
C.Create VLAN 10, assign G0/1 and G0/2 as trunk ports in VLAN 10, configure G0/3 as trunk with encapsulation dot1q and native VLAN 99.
D.Create VLAN 10, assign G0/1 and G0/2 as access ports in VLAN 10, configure G0/3 as trunk with encapsulation dot1q and native VLAN 1.
AnswerA
solution
! SW1
interface GigabitEthernet0/1
switchport access vlan 10
interface GigabitEthernet0/2
switchport access vlan 10
interface GigabitEthernet0/3
switchport trunk encapsulation dot1q
switchport trunk native vlan 99

Why this answer

VLAN 10 must be created and the access ports must be explicitly set to access mode with 'switchport mode access' before assigning them to VLAN 10. Assigning the access ports to VLAN 10 places the PCs in the correct broadcast domain. The trunk needed explicit 802.1Q encapsulation and a native VLAN change to 99 for security and consistency.

Exam trap

Be careful to distinguish between access and trunk ports: access ports belong to a single VLAN for end devices, while trunk ports carry multiple VLANs between switches. Also, remember that 802.1Q is the standard trunking protocol, and native VLAN should be changed from default 1 for security.

Why the other options are wrong

B

The specific factual error is that ISL is a legacy Cisco proprietary trunking protocol, and modern switches default to 802.1Q. The question specifies 802.1Q encapsulation.

C

The specific factual error is that ports connected to end devices (PCs) should be access ports, not trunk ports. Trunk ports are used for inter-switch links.

D

The specific factual error is that the native VLAN must be explicitly set to 99. Native VLAN 1 is the default and is often targeted in VLAN hopping attacks.

79
MCQhard

A technician is troubleshooting a network issue where hosts in VLAN 20 on SW1 cannot communicate with hosts in VLAN 20 on SW2. Both switches are connected by an Ethernet trunk link that is up/up and configured as a trunk. The VLAN databases on both switches include VLAN 20, and the spanning tree for VLAN 20 is in a forwarding state on all ports. Hosts within VLAN 20 on each switch can communicate with each other locally. What is the most likely cause?

A.The native VLAN is mismatched on the two ends of the trunk.
B.VLAN 20 has not been created in the VLAN database on SW2.
C.The trunk encapsulation is mismatched between SW1 and SW2.
D.VLAN 20 is not in the switchport trunk allowed VLAN list on the trunk port between SW1 and SW2.
AnswerD

When a trunk port’s allowed VLAN list explicitly excludes a VLAN, the switch drops all frames tagged for that VLAN, even though the VLAN exists locally and the trunk is active. This results in the described symptom of local intra-VLAN communication working but no cross-switch communication for VLAN 20.

Why this answer

The most likely cause is that VLAN 20 is not included in the allowed VLAN list on the trunk port between SW1 and SW2. Even though the trunk is up/up and VLAN 20 exists in the VLAN database, the switchport trunk allowed vlan command restricts which VLANs can traverse the trunk. If VLAN 20 is omitted from this list, frames from VLAN 20 will be dropped at the trunk, preventing inter-switch communication for that VLAN.

Exam trap

Cisco often tests the distinction between VLAN existence in the database and VLAN permission on a trunk; candidates mistakenly think that if a VLAN is created and spanning tree is forwarding, it must work, but the trunk allowed list is an independent filter that can block traffic.

Why the other options are wrong

A

Candidates may think that a native VLAN mismatch breaks all trunk functions.

B

Candidates may assume that a missing VLAN on one switch explains inter-switch failures, ignoring that local communication would also fail.

C

Candidates might overlook that the trunk link is operational, which implies matching encapsulation.

80
Matchingmedium

Drag and drop the switch port configuration commands on the left to the correct descriptions on the right.

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

Concepts
Matches

Statically configures the port as an access port

Sets the data VLAN for an access port

Assigns the VLAN for IP phone voice traffic

Permanently sets the interface as a trunk port

Restricts which VLANs traverse the trunk

Why these pairings

The command 'switchport mode access' statically sets the port as an access port. 'switchport access vlan 10' assigns VLAN 10 as the data VLAN for connected devices. 'switchport voice vlan 20' defines the VLAN used by a Cisco IP phone for voice traffic. 'switchport mode trunk' forces the port into permanent trunking mode. 'switchport trunk allowed vlan 100,200' restricts the trunk to carry only VLANs 100 and 200.

81
MCQhard

A user connects a small unmanaged switch to an access port, and the port immediately transitions to err-disabled. Which feature most likely caused this behavior?

A.UDLD aggressive
AnswerB

BPDU Guard is a spanning-tree protection feature applied to PortFast-enabled edge ports. When any BPDU is received on such a port, the switch immediately shuts the interface down and places it in an err-disabled state, because a legitimate access port should never receive BPDUs. This prevents an unauthorized user switch from participating in spanning tree and creating a Layer 2 loop.

Why this answer

BPDU Guard is the correct answer because it is specifically designed to protect access ports configured with PortFast. When an unauthorized switch is connected to such a port, BPDU Guard detects the incoming BPDU and immediately places the port into err-disabled state, preventing potential loops or topology changes. UDLD aggressive detects unidirectional links but does not cause err-disabled due to BPDU reception.

Root guard blocks ports that attempt to become the root bridge by placing them in root-inconsistent state (not err-disabled). Loop guard prevents alternate/root ports from becoming designated in the absence of BPDUs, putting the port into loop-inconsistent state, again not err-disabled.

Exam trap

Remember that BPDU Guard specifically targets BPDUs on PortFast ports, not general security or loop prevention.

Why the other options are wrong

A

UDLD aggressive detects unidirectional links but does not cause err-disabled on receiving BPDUs; it operates at Layer 1/2 for fiber links.

C

Root guard prevents a port from becoming the root bridge by moving it to root-inconsistent state, not err-disabled.

D

Loop guard prevents alternate/root ports from becoming designated when BPDUs stop, putting the port in loop-inconsistent state, not err-disabled.

82
MCQhard

A network technician is troubleshooting an inter-VLAN routing issue on a multilayer switch. Hosts on VLAN 10 can reach the SVI for VLAN 10 (10.0.10.1) but cannot reach hosts on VLAN 20. The technician has verified that 'ip routing' is enabled and that the 'show ip route' command displays directly connected routes for both VLANs. No static routes are configured. What should the technician do next?

A.Check the ARP table for entries on VLAN 20.
B.Issue the 'show ip routing' command again to confirm routing is enabled.
C.Configure a default route pointing to the next-hop gateway.
D.Verify the VLAN membership of the destination host on VLAN 20.
AnswerA

The Layer 3 routing table is correct; the problem is likely that the switch lacks a Layer 2 MAC address for the destination host on VLAN 20. Examining the ARP cache will confirm whether the switch can map the destination IP to a MAC address, and if not, will show that ARP resolution is failing, which explains the connectivity break.

Why this answer

The hosts on VLAN 10 can reach the SVI (10.0.10.1) but not hosts on VLAN 20, which indicates that Layer 3 routing is working (ip routing enabled, directly connected routes present). The issue is likely that the switch does not have the MAC address of the destination host in VLAN 20 in its ARP table, so it cannot forward frames to that host. Checking the ARP table for VLAN 20 entries will reveal whether the switch has resolved the Layer 3-to-Layer 2 address mapping for the destination.

Exam trap

Cisco often tests the misconception that if 'ip routing' is enabled and routes are present, inter-VLAN routing should work, but they trap candidates by omitting the critical step of ARP resolution, which is required to deliver frames to the destination host's MAC address.

Why the other options are wrong

B

This option revisits a step already completed and verified, making it redundant. Candidates might think double-checking routing is safe, but the scenario explicitly states routing is working as expected.

C

Some candidates might believe inter-VLAN communication requires a default route, but directly connected routes already provide full reachability without static routing. This action is overly drastic and misdirected.

D

Candidates often jump to VLAN misconfigurations when inter-VLAN communication fails, even when routing is confirmed. The scenario already establishes the VLAN 20 host's location; the next logical layer to inspect is ARP resolution.

83
MCQhard

Refer to the exhibit. A network administrator is troubleshooting connectivity to devices in VLAN 10 on a Layer 3 switch. The administrator issues the show ip interface brief command on SW1 and sees the output displayed. What is the most likely reason that the VLAN 10 SVI is not functioning?

A.No active ports are assigned to VLAN 10.
B.The VLAN 10 SVI has been administratively shut down.
C.The IP address configured on the VLAN 10 SVI is incorrect for the subnet.
D.The switch ports assigned to VLAN 10 are all configured as trunk ports.
AnswerA

The SVI for VLAN 10 will not transition to up/up until at least one switch port is in the up/up state and actively assigned to VLAN 10 (either as an access port in that VLAN or as a trunk port that has VLAN 10 allowed and active). With no active member ports, the switch considers the VLAN to have no operational Layer 2 presence, so the SVI's line protocol remains down even though the VLAN exists and is configured with an IP address. This is a standard Cisco IOS behavior: the SVI's status mirrors the presence of an active port in the associated VLAN, not merely the VLAN's existence.

Why this answer

The VLAN 10 SVI will remain in a down/down state if there are no active ports assigned to VLAN 10, because a Layer 3 switch requires at least one active Layer 2 interface in the VLAN to bring the SVI up. This is a fundamental behavior of Cisco switches: the SVI is operationally down until the VLAN has at least one active port in a non-blocking state. The show ip interface brief output would show the VLAN10 interface as 'down/down' rather than 'administratively down' or 'up/up'.

Exam trap

Cisco often tests the subtle distinction between an SVI being 'down/down' due to no active ports in the VLAN versus 'administratively down' due to a shutdown command, and candidates may incorrectly assume a misconfigured IP address or trunk port issue is the cause.

Why the other options are wrong

B

Candidates often confuse 'down' with 'administratively down', assuming any disabled interface will show 'down'. They need to distinguish the two statuses.

C

Some candidates think a misconfigured IP address can cause an interface to be down, but status does not reflect IP configuration.

D

A common misunderstanding is that trunk ports do not make a VLAN active; in reality, a trunk carrying VLAN 10 can activate the SVI as long as the trunk is up/up and the VLAN is not pruned.

84
MCQmedium

A wireless client can see two SSIDs from the same company: Corp and Guest. Which statement best explains what an SSID represents in this situation?

A.It is the wireless network name presented to clients for a specific WLAN.
B.It is the encryption algorithm securing the WLAN.
C.It is the radio antenna inside the AP.
D.It is the management IP address of the controller.
AnswerA

An SSID (Service Set Identifier) is the human-readable network name that an access point broadcasts in beacon and probe response frames so clients can identify and select a specific WLAN. It distinguishes multiple wireless networks on the same radio by presenting a unique name, up to 32 bytes, while the BSSID differentiates APs within the same SSID. This is why a wireless client sees the SSID as the network name before associating, making it the correct definition.

Why this answer

An SSID is the name that identifies a specific wireless LAN to clients. In practical terms, Corp and Guest are two different WLAN identifiers presented to users, even if they are broadcast by the same physical access point infrastructure. The SSID tells the client which wireless network it is trying to join.

This matters because people often confuse SSIDs with the access point itself or with the security protocol. The SSID is the network identifier, not the hardware or the encryption standard.

Exam trap

Do not confuse SSIDs with physical devices or security protocols; they are identifiers for networks.

Why the other options are wrong

B

The SSID is simply the network name broadcast by the access point; encryption algorithms like WPA2 or WPA3 are configured separately on the WLAN and are not part of the SSID itself.

C

An SSID is a logical identifier, not a physical component. The radio antenna is hardware that transmits and receives wireless signals, but it does not define the network name.

D

The management IP address of a wireless controller is used for administrative access to the controller, not for client connectivity. Clients use the SSID to identify and connect to a WLAN, not the controller's IP.

85
MCQhard

A network administrator implements a set of spanning-tree enhancements to secure the switching infrastructure. Later, a help desk ticket reports that a user in a remote office cannot connect to any network resources. While investigating, the administrator notices that the switch port connecting the remote office switch to the distribution switch is in a 'root-inconsistent' state and is blocking traffic. Which protection feature, if misapplied, most likely caused this issue?

AnswerB

Root Guard ensures that a port cannot become a root port. When a superior BPDU is received on a Root Guard-enabled port, the port transitions to a root-inconsistent state and blocks traffic, exactly as described in the scenario.

Why this answer

Root Guard is the correct answer because it forces an interface to be a designated port. If a switch receives a superior BPDU (indicating a root bridge with a lower bridge ID) on a Root Guard-enabled port, the port is placed into a 'root-inconsistent' state and blocks traffic to prevent the attached switch from becoming the root bridge. This matches the symptom described: a port in 'root-inconsistent' state blocking traffic after spanning-tree enhancements were applied.

Exam trap

Cisco often tests the distinction between 'root-inconsistent' (Root Guard) and 'loop-inconsistent' (Loop Guard) states, and the trap here is that candidates confuse the two or assume BPDU Guard is responsible for any BPDU-related blocking.

Why the other options are wrong

A

A loop-inconsistent state is different from the root-inconsistent state observed. Loop Guard acts when BPDUs stop arriving, not when they appear with a superior root claim.

C

While BPDU Guard also reacts to incoming BPDUs, it puts the port in err-disabled (shutdown) state, not a blocking state named 'root-inconsistent'. The symptom described is not error-disabled.

D

BPDU Filter would not cause the port to show a root-inconsistent state. The symptom is a protective blocking state, which BPDU Filter does not provide.

86
MCQhard

Two switches are configured for LACP EtherChannel. One side is set to passive and the other side is also set to passive. What is the most likely outcome?

A.The EtherChannel will not form because neither side initiates LACP negotiation.
B.The EtherChannel always forms because passive mode is preferred.
C.The links automatically become a routed interface.
D.The switches delete the bundle configuration automatically.
AnswerA

In LACP, passive mode places the port in a listening state and does not transmit negotiation packets; it only responds to incoming LACP PDUs. Since both switches are configured passive, neither sends an LACP PDU, so the negotiation never begins. Consequently, the EtherChannel remains down and the individual ports stay in their normal operational state as separate access/trunk links.

Why this answer

The EtherChannel will not form because LACP passive mode only listens for negotiation; it does not initiate it. When both sides are set to passive, neither side sends LACP packets, so the bundle cannot be established. This is a deterministic outcome, not merely unlikely.

Exam trap

Ensure at least one side is set to active in LACP configurations to avoid non-formation of the channel.

Why the other options are wrong

B

Passive mode does not initiate LACP negotiation; it only responds to incoming LACPDUs. Therefore, with both sides passive, no LACPDUs are exchanged, and the EtherChannel will not form. The statement that passive mode is preferred is incorrect; active mode is typically used on at least one side to initiate the channel.

C

LACP operates at Layer 2 and does not change the interface type. The ports remain switchports (Layer 2) unless explicitly configured with 'no switchport'. LACP mode has no effect on Layer 3 routing functionality.

D

LACP configuration is not automatically deleted when negotiation fails. The configuration remains in the running-config, and the ports will simply not form an EtherChannel. The administrator must manually remove the configuration if desired.

87
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 then recover a port that 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

Only option A correctly follows the sequence of configuring Root Guard on designated ports, Loop Guard on non-designated ports, BPDU Guard on PortFast ports, then enabling errdisable recovery globally, and finally manually re-enabling the port. Option B assigns Loop Guard to designated ports and Root Guard to non-designated ports, which is incorrect. Option C correctly assigns protections but starts with BPDU Guard, deviating from the specified order.

Option D assigns Root Guard to non-designated ports and Loop Guard to designated ports, which is incorrect.

Exam trap

The exam trap is confusing which protection goes on which port role. Remember: Root Guard protects designated ports from becoming root; Loop Guard protects non-designated ports from becoming forwarding; BPDU Guard protects PortFast ports. Also, recovery order: global first, then interface re-enable.

88
Matchingmedium

Match each wireless term to its most accurate meaning.

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

Concepts
Matches

Centralized platform used to manage access points

Name that identifies the wireless network to clients

Wireless security standard

Protocol associated with AP-to-controller communication

Why these pairings

SSID is the human-readable network name. BSSID is the unique MAC address of an AP radio. ESSID is the same SSID used across multiple APs in an extended network.

Beacons are management frames that advertise the network. Probe requests are sent by clients to find APs. Association is the process of connecting a client to an AP.

Exam trap

Do not confuse SSID with BSSID, Beacon frames, or Association. SSID is simply the network name; the other terms refer to different concepts.

89
MCQmedium

A switch interface connected to another switch must carry VLANs 10, 20, and 30 only. Which command best enforces that requirement on the trunk?

A.switchport trunk allowed vlan 10,20,30
B.switchport access vlan 10,20,30
C.switchport mode dynamic auto
D.switchport trunk native vlan 10,20,30
AnswerA

The correct command for a trunk interface is `switchport trunk allowed vlan 10,20,30`; it explicitly defines the allowed VLAN list for IEEE 802.1Q tagging. By specifying only VLANs 10, 20, and 30, the administrator ensures that frames from other VLANs are not forwarded across this trunk, providing precise traffic segmentation between the two switches.

Why this answer

The correct command is the one that explicitly sets the allowed VLAN list on the trunk. In plain language, the administrator wants the inter-switch link to carry only the named VLANs instead of every VLAN by default. Cisco trunks can transport multiple VLANs, but that does not mean every VLAN should always be permitted. Restricting the allowed list supports cleaner design and helps reduce unnecessary VLAN transport.

This is a common CCNA switching task because it distinguishes between creating a trunk and controlling what the trunk actually carries. Simply enabling trunking is not enough when the requirement names exact VLANs. The answer must directly restrict the allowed list rather than change the native VLAN or apply an unrelated access-port command.

Exam trap

A common exam trap is selecting commands that do not correctly restrict VLANs on a trunk. For example, using 'switchport access vlan 10,20,30' is invalid because access ports support only one VLAN. Another trap is confusing the native VLAN setting with allowed VLANs; 'switchport trunk native vlan' only defines the untagged VLAN and does not filter VLANs.

Also, relying on dynamic trunk negotiation commands like 'switchport mode dynamic auto' does not restrict VLANs and can lead to trunks carrying all VLANs by default. These mistakes cause VLAN traffic to flow where it shouldn’t, violating design requirements.

Why the other options are wrong

B

Incorrect because 'switchport access vlan' applies only to access ports and cannot specify multiple VLANs; it does not configure trunk VLANs.

C

Incorrect because 'switchport mode dynamic auto' controls trunk negotiation but does not limit which VLANs are allowed on the trunk.

D

Incorrect because 'switchport trunk native vlan' sets only one native VLAN for untagged traffic and does not restrict the allowed VLAN list.

90
MCQhard

An EtherChannel should form using LACP between two switches. One side is configured for LACP active, and the other side is configured for LACP active. What is the expected result if the other link settings also match?

A.The EtherChannel should form if the other interface settings are compatible.
B.The channel fails because both sides must be passive.
C.The channel becomes a routed interface automatically.
D.All VLAN tags are removed from the bundle by default.
AnswerA

A valid LACP EtherChannel can form with both switches in active mode because active interfaces actively transmit LACP protocol data units (PDUs) and negotiate the bundle. As long as the physical interface settings (speed, duplex, allowed VLANs, trunk encapsulation, and switchport mode) are consistent on both sides, the channel will come up. The active/active pairing is a standard and robust configuration for dynamic link aggregation.

Why this answer

The EtherChannel should form successfully if the underlying link settings are compatible. LACP active/active is a valid combination, as both switches actively negotiate the bundle. However, the channel does not automatically become a routed interface (option C is incorrect because EtherChannel can operate as Layer 2 or Layer 3 depending on configuration, not automatically due to LACP mode).

Additionally, VLAN tags are not removed by default from the bundle (option D is incorrect; VLAN tagging is preserved based on the switchport mode and allowed VLAN settings). The key troubleshooting point is to ensure that other interface parameters such as speed, duplex, and VLAN settings match across the member ports.

Exam trap

Don't confuse LACP active/active with incompatible settings; they are designed to negotiate successfully.

Why the other options are wrong

B

LACP passive/passive is the pairing that fails to form an EtherChannel because both sides wait for the other to initiate negotiation, resulting in no LACP PDUs being sent. Active/active is a valid and functional combination.

C

LACP operates at Layer 2 and does not change the interface type; the EtherChannel remains a Layer 2 port-channel unless explicitly configured with 'no switchport' or an IP address. The question does not mention any Layer 3 configuration.

D

EtherChannel formation does not alter VLAN tagging; if the interfaces are trunk ports, VLAN tags remain intact. The bundle simply aggregates bandwidth while preserving existing VLAN configurations.

91
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure and recover from a BPDU Guard violation on a PortFast-enabled access port using Cisco IOS-XE CLI commands.

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

Only Option A correctly lists the steps to configure and manually recover from a BPDU Guard violation on a PortFast-enabled port. Option B is invalid because the command 'clear spanning-tree bpduguard' does not exist; the proper recovery is shutdown/no shutdown. Option C incorrectly applies the global command 'spanning-tree portfast bpduguard default' in interface mode; it should be used in global configuration mode.

Option D includes an unnecessary 'Enter interface configuration mode' step after the global recovery command and does not reflect the correct sequence for automatic recovery.

Exam trap

Confusing the global default command 'spanning-tree portfast bpduguard default' with the interface command 'spanning-tree bpduguard enable'. Also, remember that the 'errdisable recovery cause bpduguard' command is a global configuration command, not a privileged EXEC command.

92
MCQhard

A wireless client can associate to the correct corporate SSID and authenticate successfully, but receives an address from the guest network instead of the employee network. Which troubleshooting area is strongest?

A.Incorrect WLAN-to-role or VLAN mapping after successful authentication.
B.The client must be using the wrong subnet mask manually.
C.The AP must be missing PPP encapsulation.
D.The issue is that STP root election failed.
AnswerA

After a wireless client successfully authenticates via methods such as 802.1X, the WLAN controller or lightweight AP maps the client to a VLAN based on the SSID's WLAN profile or RADIUS attributes like Tunnel-Private-Group-ID. If the WLAN is incorrectly bound to a guest VLAN, or the RADIUS server returns a mismatched VLAN ID, the client associates cleanly but receives an IP from the wrong subnet. This exact description matches an incorrect WLAN-to-role or VLAN mapping, which is a common configuration error in enterprise Wi-Fi.

Why this answer

The client successfully authenticates to the corporate SSID but receives an IP address from the guest network, indicating that the authentication phase is working correctly. The issue lies in the post-authentication mapping: the WLAN is likely mapped to the wrong VLAN or role (e.g., a RADIUS server attribute or local VLAN assignment is misconfigured), causing the client to be placed in the guest VLAN instead of the employee VLAN. This is a common misconfiguration in WLAN-to-VLAN or WLAN-to-role mapping after successful 802.1X authentication.

Exam trap

Cisco often tests the distinction between authentication success and post-authentication authorization (VLAN/role mapping), tricking candidates into focusing on DHCP or IP configuration issues when the real problem is the VLAN assignment after authentication.

Why the other options are wrong

B

The client receives an address from the guest network, indicating that the DHCP server or VLAN assignment is incorrect. A manually configured wrong subnet mask would not cause the client to obtain an IP from a different network; it would simply prevent proper communication within the assigned subnet. The issue is at the network assignment level, not a host configuration error.

C

PPP encapsulation is used on serial WAN links, not in wireless LAN environments. Wireless clients connect via 802.11, and APs use Ethernet or CAPWAP to connect to the network. PPP has no role in VLAN assignment or DHCP for wireless clients.

D

STP root election determines the root bridge in a switched network to prevent loops, but it does not affect VLAN assignment for wireless clients. Even if STP root election failed, it would not cause a client to receive an IP from the wrong network; it would more likely cause network instability or loops.

93
MCQhard

A network administrator recently configured BPDU Guard on all access ports of a switch to protect against rogue switches. After the change, users in VLAN 10 report intermittent connectivity issues and frequent link flaps. The administrator checks the switch and notices that several ports are in an err-disabled state. What is the most likely cause of the problem?

A.Root Guard is preventing the port from becoming a root port.
B.BPDU Guard is enabled on access ports that are receiving BPDUs, causing the ports to go into err-disabled state.
C.Loop Guard has detected a unidirectional link and placed the port into err-disabled state.
D.BPDU Guard is globally enabled but not configured on the interface, so the port is err-disabled due to a BPDU received.
AnswerB

BPDU Guard is a security feature that intentionally places a PortFast-enabled access port into err-disabled when any BPDU is received, protecting against rogue switches attempting to participate in spanning tree. When an unauthorized device sends BPDUs, the switch immediately disables the port and logs an error, requiring an administrator to manually re-enable it or rely on errdisable recovery. This matches the scenario where access ports receiving BPDUs are error-disabled.

Why this answer

BPDU Guard is configured to protect against rogue switches by placing a port into an err-disabled state upon receiving a BPDU. In this scenario, BPDU Guard is enabled on access ports that are receiving BPDUs (possibly from a rogue switch or misconfiguration), causing the ports to err-disable and flap. PortFast is not required for BPDU Guard to function; the issue is that BPDUs are being received on ports that are not expected to receive them.

The intermittent connectivity occurs as ports cycle into err-disabled and are re-enabled.

Exam trap

A common mistake is believing BPDU Guard requires PortFast to function; in reality, BPDU Guard can be enabled per-interface without PortFast and will err-disable the port when a BPDU is received.

Why the other options are wrong

A

Root Guard prevents a port from becoming a root port by placing it in a root-inconsistent state, not err-disabled. It does not cause link flaps or err-disable ports.

C

Loop Guard prevents alternate or root ports from becoming designated in the absence of BPDUs, but it does not err-disable ports. It places ports in a loop-inconsistent state, which is not err-disabled.

D

The global 'spanning-tree portfast bpduguard default' command only applies BPDU Guard to PortFast-enabled ports. If a port receives a BPDU and is not PortFast, it will not be err-disabled by this global command. The scenario states BPDU Guard was configured on all access ports, implying interface-level configuration.

94
MCQhard

A wireless client joins the correct SSID and gets an address in the correct employee subnet, but cannot reach only one internal application while everything else works. Which troubleshooting area is the strongest first target?

A.The path or policy specific to that application, since general employee connectivity already works.
B.The SSID broadcast setting, because the client must not be joined correctly.
C.The voice VLAN on the wired access port connected to the AP uplink.
D.The OSPF router ID on the client device.
AnswerA

The client has already associated to the correct SSID, authenticated, and received a valid IP address from the expected subnet, proving that the WLAN and general network path are functional. Since other employees can connect and general connectivity works, the failure is isolated to application-specific transport, such as traffic filtering rules, access control lists, firewall policies, or per-application VPN/proxy configurations. Therefore, troubleshooting should focus on the path and policies that govern that particular application.

Why this answer

The strongest first target is the application path or policy specific to that application because the client already has general connectivity: it joined the correct SSID, authenticated, and obtained an IP address in the employee subnet. A failure limited to one internal application indicates that basic WLAN join, DHCP, and overall routing are working; therefore, ACLs, firewall rules, DNS resolution for that service, or application-specific policies are the likely cause. Option B (SSID broadcast setting) is irrelevant because the client successfully joined the SSID and has connectivity.

Option C (voice VLAN on the wired access port) is not a first target because the symptom involves a single data application, not voice, and the client is on the employee subnet, not a voice VLAN. Option D (OSPF router ID on the client) is invalid because client devices do not typically run OSPF; OSPF runs on routers, not wireless clients.

Exam trap

Avoid restarting troubleshooting from basic connectivity steps when the problem is isolated to a specific application.

Why the other options are wrong

B

The client has already joined the correct SSID, authenticated, and received an IP address in the correct subnet, so the SSID broadcast setting is not the issue. The problem is specific to one application, not general connectivity.

C

The voice VLAN on the AP uplink is used for VoIP traffic, not for general data applications. Since the client can access other internal resources, the issue is not related to the AP uplink configuration.

D

OSPF router IDs are used by routers in OSPF routing, not by end-client devices. Clients do not run OSPF, so this is irrelevant to the problem.

95
PBQmedium

You are connected to SW1 via console. SW1 is a Layer 2 switch with two ports (G0/1 and G0/2) connected to a host. The host should be able to send and receive traffic on VLAN 10 and VLAN 20. Configure the two ports as a trunk link to the host, but ensure that the trunk only carries VLANs 10 and 20, and set the native VLAN to VLAN 99.

Network Topology
G0/1, G0/2HostSW1

Hints

  • Use the 'switchport trunk allowed vlan' command to restrict which VLANs are carried.
  • The native VLAN must match on both ends of the trunk.
A.interface range gigabitethernet0/1-2 switchport mode trunk switchport trunk allowed vlan 10,20 switchport trunk native vlan 99
B.interface range gigabitethernet0/1-2 switchport mode trunk switchport trunk allowed vlan 10-20 switchport trunk native vlan 99
C.interface range gigabitethernet0/1-2 switchport mode trunk switchport trunk allowed vlan 10,20 switchport native vlan 99
D.interface range gigabitethernet0/1-2 switchport mode trunk switchport trunk allowed vlan 10,20 switchport trunk native vlan 1
AnswerA
solution
! SW1
interface gigabitethernet0/1
switchport mode trunk
switchport trunk allowed vlan 10,20
switchport trunk native vlan 99
interface gigabitethernet0/2
switchport mode trunk
switchport trunk allowed vlan 10,20
switchport trunk native vlan 99

Why this answer

Configuring the ports as trunks allows multiple VLANs. The 'allowed vlan' command restricts the trunk to only VLANs 10 and 20, while 'native vlan 99' sets the untagged VLAN to 99, ensuring proper tagging and avoiding VLAN mismatch.

Exam trap

Watch out for the difference between 'switchport trunk allowed vlan 10,20' (list) and 'switchport trunk allowed vlan 10-20' (range). Also, remember that on a trunk port, the native VLAN command must include the 'trunk' keyword: 'switchport trunk native vlan'. Finally, always verify that the native VLAN is set to the required value, not left at the default.

Why the other options are wrong

B

The specific factual error is using a range (10-20) instead of a list (10,20), which includes unintended VLANs.

C

The specific factual error is omitting the 'trunk' keyword in the native VLAN command, which is required for trunk ports.

D

The specific factual error is setting the native VLAN to 1 instead of 99, which does not meet the requirement.

96
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure a router-on-a-stick topology for inter-VLAN routing between VLANs 10 and 20, using 802.1Q trunking with native VLAN 99 for management 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

Why this order

The sequence follows Cisco's best practices: VLANs are created first, then access ports are assigned to them. The switch trunk is configured with 802.1Q encapsulation and the native VLAN set to 99 before the router end. On the router, the physical interface must be enabled before subinterfaces can operate.

The native VLAN subinterface is created first to handle untagged frames, then the data VLAN subinterfaces are configured. This order avoids errors such as missing VLANs, incorrect encapsulation, and physical link down state.

97
MCQhard

Two switches should form an EtherChannel using LACP. One side is configured active and the other passive. If the port settings otherwise match, what is the expected result?

A.The EtherChannel should form if the other interface settings are compatible.
B.The EtherChannel fails because both sides must be active.
C.the bundle forms but only in PAgP mode
D.only the active side attempts to bundle
AnswerA

This is correct because active/passive is a valid LACP negotiation pairing.

Why this answer

The EtherChannel should form successfully. In plain language, active mode initiates LACP negotiation and passive mode listens and responds. Because one side is active, the negotiation can begin and the bundle can come up as long as the underlying interface settings are compatible.

This is a standard LACP pairing. The important lesson is that active/passive works, while passive/passive usually does not. The correct answer is the one that recognizes active/passive as a valid combination.

Exam trap

Remember that active/passive works for LACP, but passive/passive does not initiate negotiation.

Why the other options are wrong

C

LACP and PAgP are incompatible, so the bundle cannot form in PAgP mode when one side uses LACP.

D

The passive side will respond to LACP negotiations, so both sides participate and the bundle forms.

98
PBQmedium

You are connected to SW1 via the console. SW1 is a Layer 2 switch with two VLANs: VLAN 10 (Sales) and VLAN 20 (Engineering). Port G0/1 is connected to a sales PC, and port G0/2 is connected to an engineering PC. You need to ensure that each PC is in the correct VLAN. However, the sales PC is currently unable to ping the engineering PC because they are in different VLANs. You have a router R1 connected to SW1 via port G0/3. Configure inter-VLAN routing using Router-on-a-Stick on R1, and ensure SW1's port G0/3 is properly configured as a trunk.

Network Topology
G0/1G0/1G0/3G0/3G0/0G0/2SW1PC1VLAN 10R1PC2VLAN 20

Hints

  • Router-on-a-Stick uses subinterfaces on the router with 802.1Q encapsulation.
  • The switch port connected to the router must be configured as a trunk to carry multiple VLANs.
  • Each subinterface must have an IP address in the respective VLAN's subnet.
A.Configure subinterfaces on R1 with encapsulation dot1Q and assign IP addresses in VLAN 10 and VLAN 20. Configure SW1 interface G0/3 as a trunk port.
B.Configure a routed port on SW1 G0/3 and assign an IP address. Then configure static routes on R1 to reach each VLAN.
C.Configure SW1 interface G0/3 as an access port in VLAN 10. Then configure R1 with a single IP address in VLAN 10 and enable proxy ARP.
D.Configure SW1 interface G0/3 as a trunk port. Then configure R1 with a single IP address on the physical interface and enable VLAN routing using the 'vlan' command.
AnswerA
solution
! R1
interface GigabitEthernet0/0.10
encapsulation dot1Q 10
ip address 192.168.10.1 255.255.255.0
interface GigabitEthernet0/0.20
encapsulation dot1Q 20
ip address 192.168.20.1 255.255.255.0
interface GigabitEthernet0/0
no shutdown

! SW1
interface GigabitEthernet0/3
switchport mode trunk

Why this answer

Router-on-a-Stick allows a single router interface to route between VLANs by using subinterfaces with 802.1Q encapsulation. The switch port must be a trunk to carry the tagged frames. This configuration enables communication between VLAN 10 and VLAN 20.

Exam trap

The key trap is that candidates often forget to configure the switch port as a trunk, or they try to use a routed port on a Layer 2 switch. Also, some may think that a single IP address on the router's physical interface is sufficient, but subinterfaces are mandatory for Router-on-a-Stick.

Why the other options are wrong

B

Layer 2 switches do not support routed ports; they only support switchport mode access or trunk.

C

An access port cannot carry multiple VLANs; a trunk is required for Router-on-a-Stick.

D

Router-on-a-Stick requires subinterfaces; a single IP address on the physical interface only handles one VLAN. The 'vlan' command is not used on routers for inter-VLAN routing.

99
Matchingmedium

Drag and drop the port configuration commands/technologies on the left to their corresponding descriptions on the right.

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

Concepts
Matches

Configures the port as a non-trunking access port

Limits the number of MAC addresses on a desktop access port

Separates VoIP traffic into a dedicated VLAN

Assigns the data VLAN for desktop or AP devices

Immediately transitions an end-device port to forwarding state

Macro that sets portfast, mode access, and port-security for IoT/virtual hosts

Why these pairings

These are common Cisco IOS commands used for port configuration, each with a specific function.

Exam trap

Candidates often confuse commands that set port mode (access/trunk) with commands that assign VLANs or set encapsulation. Remember that 'switchport mode access' is the specific command to make a port an access port; other commands like 'switchport access vlan' or 'switchport trunk encapsulation' serve different purposes and do not change the port mode.

100
PBQmedium

You are connected to SW1 via the console. SW1 is a multilayer switch with SVIs for VLANs 10 (192.168.10.1/24) and 20 (192.168.20.1/24). Hosts in VLAN 10 can ping their default gateway (192.168.10.1), but cannot ping hosts in VLAN 20. You suspect IP routing is not enabled or the SVIs are not up.

Hints

  • Check if IP routing is enabled globally.
  • Verify that the SVIs are up/up.
  • Use ping with source to test connectivity between VLANs.
A.Enable IP routing on SW1 with the 'ip routing' global configuration command.
B.Configure a trunk port between SW1 and an external router, then enable routing on the router.
C.Ensure the SVIs are not shut down and have the 'no shutdown' command applied.
D.Add a static route on SW1 pointing to the VLAN 20 subnet via the VLAN 10 SVI.
AnswerA
solution
! SW1
ip routing

Why this answer

A multilayer switch requires 'ip routing' to forward packets between VLANs. Without it, the switch acts as a Layer 2 device. Enabling IP routing allows the SVIs to route traffic between VLANs.

The verification commands confirm routing is active and SVIs are operational.

Exam trap

The trap is that candidates may focus on interface status or static routes, overlooking the fundamental requirement of 'ip routing' on a multilayer switch. Remember that SVIs can be up and pingable, but without IP routing enabled, the switch cannot forward packets between VLANs.

Why the other options are wrong

B

The specific factual error is that the question states SW1 is a multilayer switch with SVIs, so it can route internally without an external router. The issue is that IP routing is not enabled on the switch itself.

C

The specific factual error is that the SVIs are already up (hosts can ping the gateway), so 'no shutdown' is not the missing step. The problem is at Layer 3 routing, not Layer 2/3 interface status.

D

The specific factual error is that directly connected networks do not require static routes; the switch automatically installs them when the SVI is up. The problem is that 'ip routing' is not enabled, so the switch does not use these routes for forwarding.

101
PBQhard

You are connected to SW1 via the console. SW1 is a Layer 2 switch connected to a PC on port G0/1. The network administrator wants to secure the port by allowing only two MAC addresses and enabling sticky MAC learning. Additionally, if a violation occurs, the port should be put into error-disabled state. Configure port security on G0/1 with maximum MAC addresses of 2, sticky learning, and shutdown violation mode.

Network Topology
G0/1SW1PC

Hints

  • Port security must first be enabled with switchport port-security.
  • Sticky MAC dynamically learns and saves MAC addresses to running-config.
A.SW1(config-if)# switchport port-security SW1(config-if)# switchport port-security maximum 2 SW1(config-if)# switchport port-security mac-address sticky SW1(config-if)# switchport port-security violation shutdown
B.SW1(config-if)# switchport port-security SW1(config-if)# switchport port-security maximum 2 SW1(config-if)# switchport port-security mac-address sticky SW1(config-if)# switchport port-security violation restrict
C.SW1(config-if)# switchport port-security SW1(config-if)# switchport port-security maximum 2 SW1(config-if)# switchport port-security mac-address sticky SW1(config-if)# switchport port-security violation protect
D.SW1(config-if)# switchport port-security SW1(config-if)# switchport port-security maximum 2 SW1(config-if)# switchport port-security mac-address 0000.1111.2222 SW1(config-if)# switchport port-security violation shutdown
AnswerA
solution
! SW1
interface GigabitEthernet0/1
switchport port-security
switchport port-security maximum 2
switchport port-security mac-address sticky
switchport port-security violation shutdown

Why this answer

Port security restricts access based on MAC addresses. The first command, `switchport port-security`, enables port security on the interface. With sticky, learned MACs are saved to the running config; `shutdown` violation mode places the port in error-disable state, requiring manual recovery.

Option A includes all required commands in the correct order. Option B uses `restrict`, which drops traffic but does not errdisable. Option C uses `protect`, which drops silently without logging.

Option D manually configures a specific MAC instead of enabling sticky learning, so it does not meet the requirement for sticky.

Exam trap

Do not confuse the three violation modes: shutdown (error-disable), restrict (drop + log), and protect (drop silently). Also, remember that sticky MAC learning is enabled with the 'mac-address sticky' command, not by manually configuring a MAC address.

Why the other options are wrong

B

The violation mode 'restrict' does not place the port in error-disabled state; it only drops traffic from unauthorized MACs and increments a counter.

C

The 'protect' mode drops violating frames but does not disable the port or generate syslog messages; it is the least restrictive violation mode.

D

The command 'switchport port-security mac-address' manually assigns a MAC address, whereas 'switchport port-security mac-address sticky' enables dynamic learning and storage of MAC addresses.

102
MCQhard

An EtherChannel uses LACP. One side is configured correctly, but the peer side has a different switchport mode on one of the member links. What is the most likely result?

A.The bundle may fail to form correctly because the member-link settings are inconsistent.
B.The switch automatically rewrites the peer configuration to match.
C.LACP converts the mismatched link into a routed interface automatically.
D.The mismatched link is placed in a spanning-tree blocking state.
AnswerA

When LACP is enabled on the local switch but the member links are not configured with identical parameters—such as speed, duplex, VLAN allowed lists, or trunk mode—the negotiation will fail or result in a suspended port-channel. LACP requires the same physical and administrative settings on every member link; otherwise, the misconfigured links will not join the channel group, and the bundle will either stay down or operate intermittently. The result is not a partial bundle but a failure to form the full port-channel as intended.

Why this answer

The most likely result is that the bundle will not form cleanly because EtherChannel requires member links to agree on important operational settings. In practical terms, LACP negotiation alone is not enough. The links also need compatible characteristics such as switchport mode, VLAN handling, speed, and duplex where relevant.

This is a common troubleshooting pattern. It tests whether you know that bundle membership depends on configuration consistency, not just on enabling LACP.

Exam trap

Do not assume LACP can resolve all configuration mismatches. Ensure all settings are consistent across member links.

Why the other options are wrong

B

Switches do not automatically rewrite peer configurations; configuration changes must be made manually or via network automation tools. LACP only negotiates parameters like speed and duplex, not switchport mode or VLAN settings.

C

LACP operates at Layer 2 and does not change the interface type; a mismatched link remains a Layer 2 interface. Converting to a routed interface requires manual configuration with 'no switchport' command.

D

This is incorrect because a switchport mode mismatch in an EtherChannel typically causes the link to be suspended or placed into an errdisable state, not into a spanning-tree blocking state. Spanning tree deals with loops, not port-channel parameter mismatches.

103
MCQhard

A client connects to an employee WLAN using 802.1X authentication. The authentication process completes successfully, but the client fails to obtain an IP address via DHCP. What is the most likely cause?

A.The client is being placed into the wrong policy or VLAN after successful authentication.
B.The WLAN is configured with the wrong SSID, which prevents DHCP packets from being forwarded.
C.The client has a static IP address manually configured, causing a DHCP conflict.
D.The access point is configured with an incorrect default gateway, preventing DHCP relay.
AnswerA

After successful 802.1X/RADIUS authentication, the controller or switch can assign a VLAN through attributes such as Tunnel-Private-Group-ID. If that assigned VLAN lacks a DHCP server or is not properly configured on the trunk, the client ends up in the wrong subnet with no usable IP. This is the strongest explanation because it directly maps the symptom to the post-authentication policy, rather than a client-side or AP-management issue.

Why this answer

Even after successful 802.1X authentication, the client may be assigned to the wrong VLAN or policy through RADIUS attributes (such as Tunnel-Type or Cisco AV-pair). If that VLAN lacks a DHCP server or correct subnet, the client will not receive an IP address. The other options describe issues that either prevent association entirely (wrong SSID) or are not typical causes in controller-based WLANs (static IP, AP gateway misconfiguration).

Exam trap

Cisco often tests the distinction between authentication success and post-authentication network access, leading candidates to focus on pre-authentication issues (like wrong PSK or RADIUS timeout) when the real problem is VLAN assignment or DHCP relay misconfiguration.

Why the other options are wrong

B

An incorrect SSID would prevent the client from associating to the WLAN at all, not allow authentication followed by DHCP failure.

C

A statically configured IP is less likely the strongest cause because the client would either not use DHCP or would obtain an APIPA address, and the issue is specifically about failing to obtain a correct address via DHCP.

D

The access point’s default gateway does not impact DHCP forwarding for client traffic; in controller-based deployments, DHCP packets are handled by the controller or bridged directly to the wired network.

104
PBQhard

You are connected to R1, a multilayer switch acting as the STP root for VLAN 10. Configure Root Guard on the designated port facing a downstream switch to prevent a rogue switch from becoming root. Also, enable Loop Guard on the uplink port to prevent STP loops, and configure BPDU Guard on a PortFast-enabled access port. Ensure that if a superior BPDU is received on the Root Guard port, it is blocked, and if a BPDU is received on the BPDU Guard port, it goes err-disabled.

Network Topology
G0/010.0.0.1/30G0/010.0.0.2/30trunkG0/1192.168.10.1/24R2R1access vlan 10SW2PC

Hints

  • Root Guard is applied on designated ports to block superior BPDUs.
  • Loop Guard is applied on root or alternate ports to prevent loops if BPDUs stop.
  • BPDU Guard with PortFast err-disables the port upon receiving any BPDU.
A.The configuration is correct; no changes are needed.
B.Root Guard should be applied on G0/0 instead of G0/1, and Loop Guard on G0/1 instead of G0/0.
C.BPDU Guard should be configured on G0/1 instead of G0/2, and Loop Guard should be removed from G0/0.
D.Root Guard should be applied on G0/2 instead of G0/1, and BPDU Guard should be removed from G0/2.
AnswerA
solution
! R1

Why this answer

R1 is the STP root for VLAN 10. The downstream port (G0/1) is a designated port, so Root Guard is correctly applied to prevent a superior BPDU from being accepted. The uplink port (G0/0) is a root port, so Loop Guard should be applied there to prevent an STP loop if BPDUs stop arriving.

The access port (G0/2) has PortFast and BPDU Guard enabled, which will err-disable the port if a BPDU is received. The current configuration is correct; no changes are needed. If a superior BPDU arrives on G0/1, Root Guard will block the port.

If a BPDU arrives on G0/2, BPDU Guard will err-disable it.

Exam trap

The trap is that candidates may think changes are needed because they misapply STP protections to the wrong port types. Remember: Root Guard on designated ports, Loop Guard on root/alternate ports, BPDU Guard on PortFast access ports.

Why the other options are wrong

B

Root Guard is only effective on designated ports; applying it to a root port would not prevent a rogue switch from becoming root. Loop Guard on a designated port is unnecessary and could cause false positives.

C

BPDU Guard on a trunk port would err-disable it upon receiving a BPDU, which is normal for trunk ports. Loop Guard on the root port is essential for loop prevention; removing it would leave the network vulnerable.

D

Root Guard on an access port would block the port if a superior BPDU is received, but access ports should not receive BPDUs if PortFast is enabled. BPDU Guard already handles that by err-disabling the port.

105
PBQhard

You are connected to a multilayer switch MLS1 via the console. Configure MLS1 so that IP phones connected to interface GigabitEthernet0/1 receive power via PoE, use VLAN 10 for data traffic, and use VLAN 20 for voice traffic, while the access port for an AP on GigabitEthernet0/2 should be placed in VLAN 30 and have PoE disabled. Verify your configuration using appropriate show commands.

Hints

  • Voice VLAN is configured with a separate command from the access VLAN.
  • PoE can be disabled per interface using 'power inline never'.
  • Use 'show interfaces switchport' to see both voice and access VLAN assignments.
A.interface GigabitEthernet0/1 switchport mode access switchport access vlan 10 switchport voice vlan 20 power inline auto ! interface GigabitEthernet0/2 switchport mode access switchport access vlan 30 power inline never
B.interface GigabitEthernet0/1 switchport mode trunk switchport trunk allowed vlan 10,20 power inline auto ! interface GigabitEthernet0/2 switchport mode access switchport access vlan 30 power inline never
C.interface GigabitEthernet0/1 switchport mode access switchport access vlan 20 switchport voice vlan 10 power inline auto ! interface GigabitEthernet0/2 switchport mode access switchport access vlan 30 power inline never
D.interface GigabitEthernet0/1 switchport mode access switchport access vlan 10 switchport voice vlan 20 power inline never ! interface GigabitEthernet0/2 switchport mode access switchport access vlan 30 power inline auto
AnswerA
solution
! MLS1
interface GigabitEthernet0/1
switchport voice vlan 20
power inline auto
interface GigabitEthernet0/2
switchport access vlan 30
power inline never

Why this answer

For the IP phone port (G0/1), you need to enable PoE (power inline auto) and configure the voice VLAN (switchport voice vlan 20) so that the phone uses VLAN 20 for voice and the access VLAN 10 for data. For the AP port (G0/2), you must change the access VLAN to 30 and disable PoE (power inline never) to prevent powering the AP through the switch. Verify with 'show interfaces switchport' to confirm voice VLAN and access VLAN settings, and 'show power inline' to check PoE status.

Exam trap

A common trap is confusing the voice VLAN command with trunking or swapping the access and voice VLANs. Also, remember that IP phones require PoE, while the AP in this scenario does not. Always verify with show commands.

Why the other options are wrong

B

The specific factual error is that IP phones typically use an access port with a voice VLAN, not a trunk port. Trunking is unnecessary and can cause compatibility issues.

C

The specific factual error is confusing the access VLAN and voice VLAN assignments. The voice VLAN is configured with 'switchport voice vlan', and the access VLAN with 'switchport access vlan'.

D

The specific factual error is reversing the PoE settings: 'power inline never' on the phone port and 'power inline auto' on the AP port.

106
MCQmedium

Which command places a switch interface into trunking mode directly instead of relying on negotiation?

A.switchport mode trunk
B.switchport access vlan 10
C.switchport mode dynamic auto
D.spanning-tree portfast
AnswerA

The switchport mode trunk command explicitly configures the interface as an 802.1Q trunk, forcing it to carry traffic for multiple VLANs over the link. This direct configuration overrides any dynamic trunking protocol (DTP) negotiation, ensuring the port advertises itself as a trunk regardless of the neighbor's default state. It is the only command among these that definitively places the interface into trunking mode without relying on remote device behavior.

Why this answer

The direct command is `switchport mode trunk`. In plain language, this tells the switch to behave as a trunk port rather than waiting to negotiate that role through DTP. That makes the administrative intent clear and avoids ambiguity. In many production environments, explicit configuration is preferred because it is easier to understand and troubleshoot than relying on negotiation behavior.

This is a core CCNA switching idea because trunks and access ports serve very different purposes. The wrong answers either describe negotiation states or commands that relate to other aspects of VLAN behavior. The best answer is the one that directly forces the interface into trunk mode instead of merely suggesting or passively waiting for trunking.

Exam trap

Be careful not to confuse commands that involve negotiation or specify encapsulation with those that directly set the mode.

Why the other options are wrong

B

The command 'switchport access vlan 10' assigns the interface to a specific access VLAN, placing it in access mode, not trunk mode. Trunk mode is required to carry multiple VLANs, and this command does not enable trunking.

C

The command 'switchport mode dynamic auto' places the interface in a mode that waits for the neighboring switch to initiate trunking via DTP. It does not directly force trunking; the interface will only become a trunk if the neighbor is set to 'dynamic desirable' or 'trunk'.

D

The command 'spanning-tree portfast' is used to speed up the transition of an access port to the forwarding state, bypassing the listening and learning phases. It has no effect on trunking mode and is unrelated to VLAN trunk configuration.

107
MCQhard

A network engineer receives a call that users in VLAN 10 on Switch B cannot ping the default gateway, which is a router on a stick connected to Switch A. The engineer checks the Spanning Tree Protocol state on the interface connecting Switch A to Switch B (GigabitEthernet0/1) and finds it is in a root-inconsistent state. Which command output best explains the cause of the issue?

A.The interface is in err-disable state due to BPDU guard.
B.Root guard is enabled and the port received a superior BPDU, causing it to become root-inconsistent.
C.Loop guard is enabled and the port is in a blocking state due to missing BPDUs.
D.The port is in a forwarding state but the VLAN is misconfigured.
AnswerB

Root guard is correctly the cause: when a port configured with root guard receives a superior BPDU (i.e., a BPDU that would make the local switch root or change the root bridge), the port is moved to a root-inconsistent state. This blocks all traffic on the port to protect the existing root bridge and prevent a rogue switch from hijacking the spanning tree. The symptom matches exactly—the port is administratively placed in this state, not in err-disable or loop-inconsistent.

Why this answer

Root guard, when enabled on a port, places that port into a root-inconsistent blocking state if it receives a superior BPDU, preventing the switch from becoming the root bridge. This root-inconsistent state stops forwarding traffic, which explains why users in VLAN 10 cannot reach the default gateway. The port remains physically up but is blocked by spanning tree, so normal interface status would not show a down state, making the root-inconsistent state the key indicator.

Exam trap

Candidates often confuse root guard with BPDU guard: BPDU guard err-disables a port upon receiving any BPDU on a PortFast port, while root guard responds to superior BPDUs by placing the port in root-inconsistent state, not err-disable.

Why the other options are wrong

A

BPDU guard causes an err-disable state, which would show the interface as down or err-disabled, not as root-inconsistent.

C

Loop guard places a port into loop-inconsistent blocking state when BPDUs stop being received, not when a superior BPDU is received.

D

A forwarding state would allow traffic; the problem here is that the port is in a blocked state due to root guard, not a misconfigured VLAN.

108
PBQmedium

You are connected to SW1 via console. SW1 is a Layer 2 switch. Port G0/1 connects to a PC that should be allowed only one MAC address. Currently, the port is configured with default settings. You need to enable port security on G0/1, set the maximum MAC addresses to 1, configure the port to shut down if a violation occurs, and ensure that the first learned MAC address is sticky (i.e., saved to the running config).

Network Topology
G0/1PCSW1

Hints

  • Port security must be enabled on an access port or trunk port.
  • The 'sticky' keyword makes the MAC address sticky and adds it to the running config.
A.interface G0/1 switchport port-security switchport port-security maximum 1 switchport port-security violation shutdown switchport port-security mac-address sticky
B.interface G0/1 switchport port-security switchport port-security maximum 1 switchport port-security violation protect switchport port-security mac-address sticky
C.interface G0/1 switchport port-security switchport port-security maximum 2 switchport port-security violation shutdown switchport port-security mac-address sticky
D.interface G0/1 switchport port-security switchport port-security maximum 1 switchport port-security violation shutdown switchport port-security mac-address 0000.1111.2222
AnswerA
solution
! SW1
interface gigabitethernet0/1
switchport port-security
switchport port-security maximum 1
switchport port-security violation shutdown
switchport port-security mac-address sticky

Why this answer

Enabling port security and setting maximum MAC addresses to 1 limits the port to one device. The violation shutdown mode disables the port if another MAC attempts to use it. Sticky MAC learning dynamically learns the first MAC and saves it to the running configuration.

Exam trap

Be careful to distinguish between the different violation modes: shutdown (disables port), protect (drops packets without notification), and restrict (drops packets and sends SNMP trap). Also, note that sticky MAC learning is different from statically configuring a MAC address; sticky learning automatically saves the learned MAC to the running config.

Why the other options are wrong

B

The violation mode 'protect' does not shut down the port; it only drops offending traffic. The question explicitly requires the port to shut down.

C

The maximum MAC addresses must be set to 1 to restrict the port to a single device. Setting it to 2 allows an additional device.

D

The command 'switchport port-security mac-address 0000.1111.2222' statically assigns a MAC address, which does not allow dynamic learning. Sticky learning is enabled with the 'sticky' keyword.

109
MCQhard

A network administrator is troubleshooting connectivity loss in a switched network. All switches run Rapid PVST+. A host connected to an access port on SwitchC can no longer reach the default gateway. The access port is configured with PortFast and BPDU Guard. The administrator checks the interface status and finds it in an err-disabled state. What is the most likely cause of this issue?

A.The root bridge election failed, causing a loop.
B.BPDU Guard detected a BPDU on a PortFast-enabled port and disabled it.
C.Rapid PVST+ is not compatible with PortFast.
D.The port is configured as a trunk but should be an access port.
AnswerB

BPDU Guard is a security feature that monitors PortFast-enabled ports for incoming BPDUs. When a BPDU is received, it immediately transitions the port to err-disabled state to prevent a potential switching loop, as a valid access port should never receive BPDUs. This exactly matches the symptom: Gi0/1 is down/err-disabled after BPDU Guard was enabled. The port will remain disabled until manually re-enabled or errdisable recovery is configured.

Why this answer

B is correct because BPDU Guard is designed to protect the spanning-tree topology by disabling a PortFast-enabled port if it receives a BPDU, placing the port in err-disabled state. Option A is incorrect: a root bridge election failure would not cause a port to err-disable; loops do not directly trigger this state without BPDU Guard. Option C is incorrect because PortFast and BPDU Guard work with all spanning-tree variants including Rapid PVST+.

Option D is incorrect: a trunk misconfiguration alone would not cause err-disable unless BPDU Guard detects a BPDU on a PortFast port.

Exam trap

Cisco often tests the misconception that PortFast and BPDU Guard are incompatible with Rapid PVST+, but in reality, PortFast is a port-level feature that works identically across all spanning-tree variants, and BPDU Guard is the mechanism that causes the err-disabled state when a BPDU is received.

Why the other options are wrong

A

A root bridge election failure would not place the port in err-disabled state; it would cause loops but not trigger BPDU Guard directly.

C

PortFast and BPDU Guard are fully compatible with Rapid PVST+; this option implies incompatibility, which is incorrect.

D

A trunk misconfiguration alone would not cause the port to go err-disable unless a BPDU is received on a PortFast-enabled port, and BPDU Guard is the specific mechanism for that.

110
Drag & Dropmedium

Drag and drop the following steps into the correct order to create VLANs, assign access ports, configure 802.1Q trunks, set the native VLAN, and verify with 'show vlan brief' and 'show interfaces trunk'.

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

VLANs must be created before assigning ports; trunking is configured after access ports; verification is the final step.

Exam trap

Do not confuse the order of VLAN creation and port assignment. VLANs must be created before ports can be assigned to them. Also, native VLAN configuration is part of trunk configuration and should be done after trunk mode is set.

111
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure Rapid PVST+ with a designated root bridge, PortFast, and BPDU Guard on access ports.

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

Why this order

Set the spanning-tree mode to Rapid PVST+: This enables Rapid PVST+ globally, a prerequisite for the root primary command to function correctly. 2. Configure the switch as the root bridge for VLAN 1: Lowers the bridge priority to guarantee this switch becomes the root, defining the STP topology. 3.

Enter interface configuration mode for the access ports: Prepares the specific ports where PortFast and BPDU Guard are applied. 4. Enable PortFast on the interfaces: Allows immediate transition to forwarding state, bypassing listening/learning phases. 5. Enable BPDU Guard on the interfaces: Protects the network by err-disabling the port if a BPDU is received, which should occur only after PortFast is enabled on access ports.

112
Multi-Selecthard

A trunk link between two switches is up, but hosts in VLAN 30 on opposite switches cannot communicate. VLAN 10 works across the same trunk. Which two causes are the most likely?

Select 2 answers
A.VLAN 30 is not allowed on the trunk on one side
B.VLAN 30 may not exist in the VLAN database on the affected switch
C.The trunk native VLAN should always be 30
D.PortFast must be disabled on the access ports in VLAN 30
AnswersA, B

A trunk port has an allowed VLAN list, and both ends must include VLAN 30 in that list for its traffic to cross the link. If one switch's trunk configuration omits VLAN 30 (via the allowed vlan command), the trunk remains up and carries other VLANs, but frames tagged with VLAN 30 are discarded at that port. This mismatch is a frequent cause of a single VLAN failing while the trunk itself appears operational.

Why this answer

When one VLAN fails but others work across the same trunk, the problem is likely VLAN-specific. VLAN 30 may not exist on one switch or may not be allowed on the trunk. Option C is incorrect because the native VLAN does not need to be 30; a native VLAN mismatch would typically cause connectivity issues on all VLANs, not just VLAN 30.

Option D is incorrect because PortFast only affects the speed at which an access port enters the forwarding state and does not impact communication across an already-up trunk.

Exam trap

Don't assume trunk issues affect all VLANs equally; check for VLAN-specific settings.

Why the other options are wrong

C

The native VLAN ID is not required to match the VLAN that is having connectivity issues; native VLAN is used for untagged traffic on the trunk and does not affect communication for specific VLANs like VLAN 30.

D

PortFast is used on access ports to speed up the transition to forwarding state and is unrelated to inter-VLAN communication across a trunk. Disabling PortFast would not resolve connectivity issues for VLAN 30 hosts on different switches.

113
Matchingmedium

Drag and drop the items on the left to match the descriptions on the right.

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

Concepts
Matches

Enables a port as an 802.1Q trunk port

The VLAN that carries untagged frames on a trunk link

Open standard for VLAN tagging on Ethernet frames

Process of forwarding traffic between different VLANs

Displays a summary of VLANs and their assigned ports

Why these pairings

VLANs segment a switch into multiple broadcast domains. 802.1Q trunking encapsulates frames with a VLAN tag, while the native VLAN carries untagged traffic. 'switchport mode trunk' configures a trunk port, 'show vlan brief' lists VLAN assignments, and inter-VLAN routing enables communication between VLANs typically using a router or Layer 3 switch.

114
MCQhard

A switch port is configured with `switchport voice vlan 150` and `switchport access vlan 20`. Which statement best explains the design purpose?

A.It separates voice and data traffic on the same edge port by assigning them to different VLANs.
B.It turns the port into a routed WAN interface.
C.It forces the phone to use CAPWAP before receiving power.
D.It makes VLAN 150 the native VLAN on all trunks automatically.
AnswerA

The `switchport voice vlan 150` command marks the port as a Cisco Unified Communications access port, so it instructs an attached IP phone to tag its voice frames with VLAN 150 while the PC behind the phone remains untagged on the data VLAN. As a result, voice and data traffic share the same physical cable but are isolated into separate Layer 2 broadcast domains, allowing distinct QoS policies, subnets, and security controls to be applied independently.

Why this answer

The design purpose is to let the switch support a phone and an attached workstation on the same physical access port while placing their traffic into different VLANs. In practical terms, the phone can use the voice VLAN while the user's data traffic uses the access VLAN. This is a common enterprise edge design for IP telephony.

The key idea is role separation on one port, not trunking the port as a normal inter-switch link.

Exam trap

Avoid confusing voice VLAN configurations with trunking or prioritization settings.

Why the other options are wrong

B

The commands `switchport voice vlan 150` and `switchport access vlan 20` are used on a Layer 2 switch port, not a routed interface. A routed WAN interface would require `no switchport` and an IP address configuration, which is not present here.

C

CAPWAP (Control and Provisioning of Wireless Access Points) is a protocol used for wireless LAN controller and access point communication, not for voice VLAN configuration. The voice VLAN feature is unrelated to CAPWAP.

D

The `switchport voice vlan` command only affects the specific access port where it is configured, not all trunk ports. The native VLAN on trunks is configured separately with `switchport trunk native vlan`.

115
PBQhard

You are connected to SW1. The network has experienced a spanning-tree topology change, and the new root bridge is not the intended core switch. Configure SW1 with a root primary priority, enable PortFast and BPDU Guard on interface GigabitEthernet0/3 (an edge port connected to a server), and verify that a specific port in the topology is blocking. Then, after a BPDU violation occurs on G0/3, recover the interface from err-disable state without reloading the switch.

Network Topology
G0/0G0/0G0/1G0/0G0/2G0/0G0/3SW1SW2SW3SW4Server

Hints

  • Use 'spanning-tree vlan 1 root primary' to set priority to 24576.
  • PortFast and BPDU Guard are configured under the interface.
  • To recover from err-disable, you can use 'shutdown' and 'no shutdown' on the interface.
A.spanning-tree vlan 1 root primary; interface GigabitEthernet0/3; spanning-tree portfast; spanning-tree bpduguard enable; interface GigabitEthernet0/3; shutdown; no shutdown
B.spanning-tree vlan 1 priority 4096; interface GigabitEthernet0/3; spanning-tree portfast; spanning-tree bpduguard enable; interface GigabitEthernet0/3; errdisable recovery cause bpduguard
C.spanning-tree vlan 1 root secondary; interface GigabitEthernet0/3; spanning-tree portfast; spanning-tree bpduguard enable; interface GigabitEthernet0/3; no shutdown
D.spanning-tree vlan 1 root primary; interface GigabitEthernet0/3; spanning-tree portfast; spanning-tree bpdufilter enable; interface GigabitEthernet0/3; shutdown; no shutdown
AnswerA
solution
! SW1
configure terminal
spanning-tree vlan 1 root primary
interface GigabitEthernet0/3
spanning-tree portfast
spanning-tree bpduguard enable
end
configure terminal
interface GigabitEthernet0/3
shutdown
no shutdown
end

Why this answer

The current root bridge has priority 32769, but the intended root should be SW1 with a lower priority. First, configure SW1 as root primary using 'spanning-tree vlan 1 root primary' or manually set priority to 24576. For edge port Gi0/3, enable PortFast with 'spanning-tree portfast' and BPDU Guard with 'spanning-tree bpduguard enable'.

After the BPDU violation, the port is err-disabled. To recover, first shut down and then no shut the interface, or use 'errdisable recovery cause bpduguard' and wait for the recovery interval, but the most direct method is to manually bounce the interface.

Exam trap

Watch out for confusing root primary vs root secondary, BPDU Guard vs BPDU filter, and the correct method to recover an err-disabled port. Manual shutdown/no shutdown is immediate, while errdisable recovery relies on a timer.

Why the other options are wrong

B

The priority value 4096 is not used by the root primary command; it sets priority to 24576. Additionally, errdisable recovery does not immediately recover the port; it requires a timer.

C

Root secondary makes the switch a secondary root, not primary. An err-disabled port requires a shutdown before no shutdown to clear the error state.

D

BPDU filter does not trigger err-disable on BPDU reception; it silently drops BPDUs. BPDU Guard is needed to protect edge ports.

116
Matchingmedium

Match each Layer 2 protection feature to its most accurate purpose.

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

Concepts
Matches

Limits and controls MAC address use on a switch port

Disables an edge port if a BPDU is received

Helps block rogue DHCP activity and build trusted bindings

Validates ARP traffic using trusted information

Why these pairings

Storm Control limits excessive traffic. Port Security limits MAC addresses. DHCP Snooping blocks unauthorized DHCP servers.

DAI validates ARP packets. IP Source Guard filters IP traffic based on DHCP snooping. 802.1X authenticates devices before granting access.

117
MCQhard

A network engineer configures an EtherChannel between two switches. Switch A's interface is set with channel-group 1 mode active, while Switch B's identical interface is set with channel-group 1 mode auto. When verifying with show etherchannel summary, the engineer observes that the port-channel interface is down and the physical interfaces are not bundled. What is the most likely cause of the problem?

A.The LACP system priority on the active side must be lower than the auto side.
B.The mode 'auto' is a PAgP negotiation mode that is incompatible with the LACP active mode.
C.LACP requires one side to be active and the other passive; two active interfaces will not bundle.
D.The physical interfaces must be shut down and then re-enabled after configuring LACP for the bundle to form.
AnswerB

The mode 'auto' is one of the two PAgP negotiation modes (the other being 'desirable'), whereas LACP uses 'active' and 'passive'. PAgP and LACP are entirely separate protocols with different frame formats and state machines, so an interface set to 'auto' cannot form an EtherChannel with an interface set to 'active'. To create a bundle with LACP, both sides must use LACP modes, such as active/active or active/passive, not PAgP modes.

Why this answer

'active' is an LACP mode that initiates negotiations, while 'auto' is a PAgP mode that passively waits for PAgP packets. Since LACP and PAgP are incompatible protocols, the interfaces will never negotiate a bundle, leaving the port-channel down. The engineer must use matching protocol modes (e.g., both LACP active/passive or both PAgP desirable/auto) for EtherChannel to form.

Exam trap

Cisco often tests the confusion between LACP and PAgP mode keywords, especially the similarity between 'active' (LACP) and 'auto' (PAgP), leading candidates to assume they are compatible or to focus on priority or interface state rather than protocol mismatch.

Why the other options are wrong

A

LACP priority is not required for basic negotiation and does not cause a failure to bundle.

C

Active/active LACP successfully negotiates, so this is not the cause.

D

Bouncing interfaces is not required to trigger LACP negotiation.

118
PBQhard

You are connected to SW1 via console. SW1 is a Layer 2 switch connected to SW2 via three links (G0/1, G0/2, G0/3) that should form an EtherChannel using LACP. Currently, the interfaces are configured as access ports in VLAN 1. Configure the three interfaces as a LACP EtherChannel trunk that carries VLANs 1-100, and ensure the port-channel interface is operational.

Network Topology
G0/1G0/1linksSW1SW2

Hints

  • Create the port-channel interface first, then assign physical ports with 'channel-group'.
  • Use 'mode active' for LACP.
A.interface port-channel 1 switchport mode trunk switchport trunk allowed vlan 1-100 interface range g0/1-3 channel-group 1 mode active switchport mode trunk
B.interface port-channel 1 switchport mode trunk switchport trunk allowed vlan 1-100 interface range g0/1-3 channel-group 1 mode passive switchport mode trunk
C.interface port-channel 1 switchport mode access switchport access vlan 1 interface range g0/1-3 channel-group 1 mode active switchport mode trunk
D.interface port-channel 1 switchport mode trunk switchport trunk allowed vlan 1-100 interface range g0/1-3 channel-group 1 mode on switchport mode trunk
AnswerA
solution
! SW1
interface port-channel 1
switchport mode trunk
switchport trunk allowed vlan 1-100
interface gigabitethernet0/1
channel-group 1 mode active
interface gigabitethernet0/2
channel-group 1 mode active
interface gigabitethernet0/3
channel-group 1 mode active

Why this answer

The port-channel interface is created and configured as a trunk with allowed VLANs. Physical interfaces are assigned to the channel-group with LACP active mode, which negotiates the EtherChannel with the peer. The trunk is then operational for VLANs 1-100.

Exam trap

Remember that LACP requires at least one side to be in active mode to initiate negotiation. Also, the port-channel interface configuration must match the physical interfaces' switchport mode. Do not confuse 'mode on' (static) with LACP modes.

Why the other options are wrong

B

The specific factual error: LACP passive mode does not initiate negotiation; it only responds. For the EtherChannel to form, at least one side must be active.

C

The specific factual error: The port-channel interface and physical interfaces must have consistent switchport mode configuration. Here, the port-channel is access while physical are trunk, causing a mismatch.

D

The specific factual error: 'channel-group mode on' creates a static EtherChannel without LACP. The question requires LACP, so this does not meet the requirement.

119
MCQhard

An IP phone connected to switch port Gi0/4 is working and receiving calls, but the PC connected to the phone's data port cannot obtain an IP address. The technician confirms that interface Gi0/4 has switchport mode access and shows switchport access vlan 10 and switchport voice vlan 100. What should the technician do next?

A.Verify the DHCP scope for VLAN 10 on the DHCP server.
B.Verify that CDP is enabled on the IP phone.
C.Verify the QoS trust state on the switch port.
D.Verify the IP phone's passthrough mode for the PC port.
AnswerD

The IP phone acts as a switch; if the phone's PC port is not configured to pass traffic untagged on the correct VLAN (passthrough mode), the PC's frames will be dropped or placed in the wrong VLAN. Checking this setting directly addresses the path from PC to switch.

Why this answer

The PC connected to the IP phone's data port cannot obtain an IP address because the phone's internal switch (passthrough mode) is likely not forwarding traffic from the PC port to the upstream switch. The switch port is correctly configured with access VLAN 10 for data and voice VLAN 100 for voice, so the issue is not with the switch configuration but with the phone's ability to pass data traffic. Verifying the IP phone's passthrough mode ensures the PC port is enabled and forwarding frames to the switch.

Exam trap

Cisco often tests the misconception that a working phone implies all features are functional, but the PC port is a separate logical path that can be independently disabled or misconfigured.

Why the other options are wrong

A

Assumes the switch port configuration alone guarantees proper VLAN delivery to the PC, ignoring the phone's role as a transparent bridge.

B

Confuses the mechanism for voice VLAN assignment with the requirement for data passthrough; CDP's role is only for the phone's own voice VLAN, not for the PC's data VLAN.

C

Misapplies QoS as a potential cause for a connectivity issue; it is a quality-of-service feature and does not block DHCP or initial network access.

120
MCQhard

A switchport on one side of a link is configured as a trunk, but the peer side is configured as an access port. The physical link is up, but VLAN traffic behaves unexpectedly. What is the most likely cause?

A.The two ends disagree on whether the link is a trunk or an access port.
B.The switches must both use the same hostname.
C.The native VLAN must be set to 1 on both sides first.
D.The ports need OSPF enabled.
AnswerA

A switchport in trunk mode encapsulates frames with 802.1Q tags and expects to receive tagged frames, while an access port transmits and receives only untagged frames in a single VLAN. When one end is a trunk and the other is an access port, the access port will drop tagged frames or treat them as invalid, and the trunk port may not accept the untagged frames sent by the access side. This role mismatch prevents proper VLAN segmentation and causes the link to fail at Layer 2.

Why this answer

The most likely cause is a switchport mode mismatch. In practical terms, one side expects the link to carry multiple VLANs with tagging behavior, while the other side treats it as a normal one-VLAN endpoint-style access connection. The physical interface can still come up, but the two ends do not agree on how the traffic should be handled.

This is a classic Layer 2 troubleshooting pattern. The link may not be fully down, but the configuration disagreement causes logical forwarding problems.

Exam trap

Be cautious of assuming all VLAN issues are due to allowed lists or STP. Consider mode mismatches when the link is physically up but traffic is disrupted.

Why the other options are wrong

B

OSPF is a Layer 3 routing protocol used for exchanging routes between routers, not for resolving Layer 2 switchport mismatches. This issue is purely about trunk/access configuration, which is unrelated to OSPF.

C

While native VLAN mismatch can cause issues on a trunk link, the primary problem here is that one side is configured as access, not trunk. Even if native VLAN is set to 1 on both sides, the access port will still not process tagged frames correctly.

D

Hostnames are purely for identification and have no impact on switchport operation or VLAN tagging. The trunk/access mismatch is a Layer 2 configuration issue independent of hostnames.

121
Multi-Selectmedium

Which TWO statements correctly describe the configuration and effect of Root Guard and BPDU Guard on a Cisco switch?

Select 2 answers
A.Root Guard is configured on a per-port basis and causes the port to become root-inconsistent if a superior BPDU is received.
B.BPDU Guard prevents loops by disabling a trunk port that receives a BPDU from an unauthorized switch.
C.Root Guard places a port in errdisable state when a superior BPDU is received.
D.BPDU Guard is commonly enabled on ports where PortFast is configured to prevent unexpected BPDUs from causing a bridging loop.
E.Both Root Guard and BPDU Guard filter BPDUs to prevent them from being processed by the switch CPU.
AnswersA, D

Root Guard is configured per interface, usually on designated ports, to enforce the current root bridge location. When a port receives a superior BPDU, Root Guard changes the port to a root-inconsistent state, which is a blocking state for all traffic. This prevents an unauthorized switch from taking over as root, and the port resumes normal forwarding automatically after the superior BPDUs cease. It does not require errdisable or manual recovery, as it is not a security violation.

Why this answer

Root Guard is configured per interface using the 'spanning-tree guard root' command. When a port with Root Guard enabled receives a superior BPDU (one that would cause the switch to become a non-root bridge), the port is placed into a root-inconsistent state, effectively blocking traffic on that port and preventing the switch from accepting a new root bridge from that direction. This protects the spanning-tree topology from unauthorized or misconfigured switches attempting to become the root bridge.

Option D is correct because BPDU Guard is commonly enabled on ports with PortFast (typically access ports connected to end devices). When a BPDU is received on such a port, BPDU Guard places the port into errdisable state, preventing potential bridging loops that could result from an unauthorized switch connecting to the network. Option B is incorrect because BPDU Guard does not prevent loops by disabling a trunk port; it is typically used on access ports (often with PortFast) and disables the port upon receiving any BPDU, not just on trunk ports.

Option C is incorrect because Root Guard places the port into root-inconsistent state (not errdisable) when a superior BPDU is received; BPDU Guard uses errdisable. Option E is incorrect because neither Root Guard nor BPDU Guard filters BPDUs; Root Guard reacts to superior BPDUs by blocking the port, and BPDU Guard reacts to any BPDU by disabling the port. Both features allow BPDUs to be processed but then take action based on the received BPDUs.

Exam trap

Cisco often tests the distinction between the states triggered by Root Guard (root-inconsistent) versus BPDU Guard (errdisable), and candidates frequently confuse the two, assuming both place the port into errdisable or that Root Guard uses errdisable.

Why the other options are wrong

B

BPDU Guard does not prevent loops by disabling a trunk port; it is typically used on access ports with PortFast and disables the port upon receiving any BPDU.

C

Root Guard places the port into root-inconsistent state, not errdisable; errdisable is the state used by BPDU Guard.

E

Neither Root Guard nor BPDU Guard filters BPDUs; they both process received BPDUs and then take action (root-inconsistent for Root Guard, errdisable for BPDU Guard).

122
PBQhard

You are connected to SW1. A LACP EtherChannel between SW1 and SW2 has already been configured using interfaces GigabitEthernet0/1 and GigabitEthernet0/2 with channel-group 1 mode active on both sides and assigned to VLAN 100. However, the channel is not forming because of a speed/duplex mismatch. The correct interface settings for this network are speed 1000 and duplex full. Interface GigabitEthernet0/1 is already configured with these settings. Only interface GigabitEthernet0/2 needs to be corrected. Identify the configuration change needed to resolve the mismatch and verify the EtherChannel is up with 'show etherchannel summary'.

Network Topology
Gi0/1Gi0/1EtherChannelSW1SW2

Hints

  • Check the speed and duplex settings on both member interfaces.
  • LACP requires all ports in the channel to have identical configuration.
  • Use the 'show interfaces status' command to quickly see speed/duplex mismatches.
A.Configure interface GigabitEthernet0/2 with 'speed 1000' and 'duplex full', then verify the EtherChannel is up.
B.Configure interface GigabitEthernet0/1 with 'speed 100' and 'duplex half', then verify the EtherChannel is up.
C.Configure interface GigabitEthernet0/2 with 'speed auto' and 'duplex auto', then verify the EtherChannel is up.
D.Configure interface GigabitEthernet0/2 with 'channel-group 1 mode active' and 'switchport access vlan 100', then verify the EtherChannel is up.
AnswerA
solution
! SW1
interface GigabitEthernet0/2
speed 1000
duplex full
end
show etherchannel summary

Why this answer

The EtherChannel is not forming because GigabitEthernet0/2 is configured with speed 100 and duplex half, while GigabitEthernet0/1 is speed 1000 and duplex full. LACP requires all member ports to have identical speed and duplex settings. To fix this, configure GigabitEthernet0/2 with speed 1000 and duplex full, matching GigabitEthernet0/1.

After correction, the ports should bundle in Port-channel1 and show as bundled (P) in 'show etherchannel summary'.

Exam trap

The trap is that candidates may overlook the speed/duplex mismatch and focus only on the LACP mode or VLAN configuration. Always verify that all physical parameters match before troubleshooting EtherChannel formation.

Why the other options are wrong

B

The specific factual error is that the question implies the correct configuration should use speed 1000 and duplex full, not downgrade to 100/half. Also, LACP requires identical settings, but the goal is to match the higher speed.

C

The specific factual error is that auto-negotiation does not guarantee matching settings when one side is manually configured. The mismatch would persist.

D

The specific factual error is that the question explicitly states a speed/duplex mismatch prevents the channel from forming, and this option does not correct that mismatch.

123
PBQhard

You are connected to a multilayer switch SW1 via console. SW1 has an IP phone and an access point connected to interfaces GigabitEthernet0/1 and GigabitEthernet0/2 respectively. Configure the access ports so that the IP phone receives a voice VLAN (VLAN 110) and PoE priority critical, and the access point receives PoE priority high. Verify your configuration using show interfaces switchport and show power inline.

Network Topology
G0/1G0/2SW1IP PhoneAccess Point

Hints

  • Voice VLAN is configured under the access port interface with the 'switchport voice vlan' command.
  • PoE priority is set per interface using 'power inline priority'.
  • Use 'show interfaces switchport' to verify voice VLAN assignment.
A.interface GigabitEthernet0/1 switchport mode access switchport access vlan 10 switchport voice vlan 110 power inline priority critical ! interface GigabitEthernet0/2 switchport mode access power inline priority high
B.interface GigabitEthernet0/1 switchport mode trunk switchport trunk allowed vlan 10,110 power inline priority critical ! interface GigabitEthernet0/2 switchport mode access power inline priority high
C.interface GigabitEthernet0/1 switchport mode access switchport access vlan 110 switchport voice vlan 10 power inline priority critical ! interface GigabitEthernet0/2 switchport mode access power inline priority high
D.interface GigabitEthernet0/1 switchport mode access switchport access vlan 10 switchport voice vlan 110 power inline priority high ! interface GigabitEthernet0/2 switchport mode access power inline priority critical
AnswerA
solution
! SW1
interface GigabitEthernet0/1
switchport voice vlan 110
power inline priority critical
exit
interface GigabitEthernet0/2
power inline priority high
end

Why this answer

The IP phone requires a voice VLAN configured with the switchport voice vlan command. PoE priority is set per interface using power inline priority. For the phone, the priority is critical; for the AP, it is high.

Verification with show interfaces switchport confirms voice VLAN, and show power inline shows priority settings.

Exam trap

The exam trap is mixing up the voice VLAN and access VLAN assignments, or confusing PoE priority levels. Remember that the voice VLAN is configured with switchport voice vlan, not as the access VLAN. Also, note that IP phones typically use access ports with voice VLAN, not trunks.

PoE priority critical is reserved for critical devices like phones, while high is for other important devices like APs.

Why the other options are wrong

B

The specific factual error is using trunk mode for an IP phone port instead of access mode with voice VLAN.

C

The specific factual error is reversing the VLAN assignments: the access VLAN should be data, and the voice VLAN should be voice.

D

The specific factual error is swapping the PoE priority values: the phone should be critical, the AP high.

124
MCQhard

Refer to the exhibit. A network engineer expects SW1 to be the root bridge for VLAN 1, but the show spanning-tree vlan 1 output on SW2 shows that SW2 is the root. What is the most likely cause of this issue?

A.SW1 is configured with a priority of 32769 but has a higher MAC address than SW2.
B.Spanning tree is disabled on SW1 for VLAN 1.
C.SW1 has a bridge priority of 4096, but BPDU guard is configured on SW2's port to SW1, causing the port to be err-disabled.
D.The trunk link between SW1 and SW2 is down.
AnswerD

The missing root port and the fact that SW2 sees itself as root confirm that SW2 is not receiving any BPDUs from SW1. This is exactly the behavior when the inter-switch trunk is physically down, breaking the spanning-tree topology.

Why this answer

If the trunk link between SW1 and SW2 is down, SW2 will not receive BPDUs from SW1. Without BPDUs, SW2 assumes it is the root bridge for VLAN 1 (since every switch defaults to root for its own VLANs). This explains why SW2's show spanning-tree output shows itself as root, even if SW1 has a lower bridge priority.

Exam trap

Cisco often tests the misconception that a lower priority always guarantees root bridge status, but the trap here is that a failed link prevents BPDU exchange, causing the switch with the higher bridge ID to become root by default.

Why the other options are wrong

A

Candidates focus on the matching priority numbers and overlook the missing root port that indicates a complete loss of BPDUs.

B

Candidates may assume no BPDUs means STP is off, but the intended root designation suggests STP is on and a physical disconnect is the primary suspect.

C

Candidates recall that BPDU guard can block ports, but they fail to differentiate between a missing port due to err-disable and a missing port due to a physically down link, which looks identical in this output.

125
Multi-Selectmedium

Which two statements accurately describe a controller-based WLAN compared with a set of independently managed APs?

Select 2 answers
A.It centralizes management and policy across multiple access points.
B.It can improve consistency when deploying WLAN settings across many APs.
C.It removes the need for access points entirely.
D.It replaces the need for DHCP on all client devices.
E.It is the same thing as WPA3.
AnswersA, B

In a controller-based WLAN, the controller (WLC) acts as the central point for enforcing security policies, QoS, access control lists, and radio parameters across all attached access points. This centralized model gives administrators a single interface to apply and manage network-wide policies, rather than configuring each AP individually, which is a fundamental architectural benefit over autonomous AP deployments.

Why this answer

A controller-based WLAN centralizes operational control and helps apply policies more consistently across many APs. In practical terms, this improves scalability and reduces the burden of touching each AP individually when changes are needed. The APs still provide the radio service, but they are coordinated under a shared management model.

This question is about architecture, not about claiming that a controller replaces APs or that it removes all other network services.

Exam trap

A common exam trap is assuming that a controller-based WLAN eliminates the need for access points or other network services like DHCP. Some candidates mistakenly believe the controller replaces APs entirely, but APs remain essential for providing wireless connectivity. Others confuse controller-based management with wireless security protocols such as WPA3, which are unrelated concepts.

Misunderstanding these distinctions can lead to incorrect answers by conflating architecture roles with security features or network services.

Why the other options are wrong

C

Option C is incorrect because access points are still required to provide the actual wireless radio connectivity; the controller does not replace APs.

D

Option D is incorrect since DHCP or other IP configuration methods are still needed for client devices; the controller does not replace these network services.

E

Option E is incorrect because WPA3 is a wireless security standard and does not relate to the architectural concept of controller-based WLAN management.

126
PBQhard

You are connected to SW1. Two switches, SW1 and SW2, are connected via four GigabitEthernet links. Configure LACP EtherChannel between them using interfaces GigabitEthernet0/1 through GigabitEthernet0/4 on SW1. Set the channel-group mode to active on SW1. The port-channel interface must be configured as a trunk, allowing VLANs 10, 20, 30. However, the EtherChannel is not forming. The current configuration is shown below. Identify and fix the issue, then verify the EtherChannel is operational.

Network Topology
Gi0/1-4Gi0/1-44x linksSW1SW2

Hints

  • Compare the Layer 2/Layer 3 status of the port-channel interface with the member interfaces.
  • Check the 'show etherchannel summary' flags: 'SD' means Layer 3 and down; 'SU' means Layer 2 and up.
  • The port-channel interface must match the operational mode (Layer 2) of the member switchports.
A.Remove 'no switchport' and IP address from Port-channel1, then configure 'switchport mode trunk' and 'switchport trunk allowed vlan 10,20,30'.
B.Change the channel-group mode on the member interfaces from active to passive.
C.Add the 'switchport nonegotiate' command to the member interfaces.
D.Configure the member interfaces with 'channel-group 1 mode on' instead of active.
AnswerA
solution
! SW1
interface Port-channel1
no ip address 192.168.1.1 255.255.255.0
no no switchport
switchport mode trunk
switchport trunk allowed vlan 10,20,30

Why this answer

The EtherChannel is not forming because the Port-channel1 interface is configured as a Layer 3 interface (no switchport, IP address), while the member interfaces are Layer 2 switchports (switchport mode trunk). This mismatch prevents the channel from bundling. To fix this, configure Port-channel1 as a Layer 2 trunk interface with the same allowed VLANs.

The solution: remove the no switchport command and the IP address, then apply switchport mode trunk and switchport trunk allowed vlan 10,20,30. After correction, the ports should bundle and the show etherchannel summary will show the ports as bundled (P) and the port-channel as Layer 2 (S).

Exam trap

The exam trap is that candidates often focus on LACP modes or trunk negotiation but overlook the Layer 2/Layer 3 mismatch between the port-channel interface and member interfaces. Always ensure the port-channel interface is configured as either Layer 2 or Layer 3 to match the member ports.

Why the other options are wrong

B

The specific factual error: The problem is a Layer 2/Layer 3 mismatch, not the LACP mode. Active mode is valid and commonly used.

C

The specific factual error: 'switchport nonegotiate' affects trunk negotiation, not EtherChannel bundling.

D

The specific factual error: The mode change does not fix the interface type mismatch; the port-channel must be Layer 2 to match the member ports.

127
MCQmedium

A network engineer is troubleshooting a connectivity issue between two hosts on different VLANs. The engineer captures traffic on an IOS-XE router's GigabitEthernet0/1 interface using embedded packet capture (EPC). The output shows ARP requests from Host A (192.168.1.10) but no ARP replies from Host B (192.168.2.20). What is the most likely cause of this issue?

A.The router's interface is configured as an access port instead of a trunk.
B.The router's interface does not have an IP address configured in the VLAN 2 subnet.
C.Host A is in a different VLAN than the router's interface.
D.The router's interface has a duplex mismatch with the switch.
AnswerB

For inter-VLAN routing, the router must have an IP address in each VLAN's subnet to act as the default gateway and respond to ARP requests. Without an IP in VLAN 2, it cannot reply to ARP requests for 192.168.2.20.

Why this answer

The router's GigabitEthernet0/1 interface must have an IP address in the same subnet as Host B (192.168.2.20) to act as the default gateway for VLAN 2. Without an IP address in the VLAN 2 subnet, the router cannot respond to ARP requests for that subnet, so Host A's ARP requests for Host B go unanswered. This is the most likely cause because the router performs inter-VLAN routing only when it has an interface (or subinterface) with an IP address in the destination VLAN's subnet.

Exam trap

Cisco often tests the misconception that a router automatically routes between VLANs if it is connected to a switch via a trunk, but the router must have an IP address in each VLAN's subnet to respond to ARP and forward traffic.

Why the other options are wrong

A

The router's interface is a routed port, not a switchport; access/trunk concepts apply to switch interfaces. Even if it were a switch interface, the issue is about ARP replies, which require Layer 3 addressing, not trunking.

C

ARP requests are Layer 2 broadcasts; if the router's interface is in the same VLAN as Host A, it will receive the request. The problem is that the router does not reply, indicating it lacks an IP in the destination subnet.

D

Duplex mismatch causes CRC errors and collisions, but ARP requests would still be received and could be replied to. The capture shows clean ARP requests with no replies, pointing to a Layer 3 issue, not physical layer.

128
MCQhard

A switch port connected to a user PC should be placed in VLAN 20 and must not negotiate trunking. Which configuration is the most appropriate?

A.switchport mode access switchport access vlan 20
B.switchport mode trunk switchport trunk native vlan 20
C.switchport mode dynamic desirable switchport trunk allowed vlan 20
D.no switchport ip address 192.168.20.1 255.255.255.0
AnswerA

This is the correct configuration for a host port. `switchport mode access` unconditionally sets the interface as a nontrunking Layer 2 access port, disabling Dynamic Trunking Protocol (DTP) and preventing the port from becoming a trunk. The `switchport access vlan 20` command then statically assigns the port to VLAN 20, so the connected PC’s untagged frames are carried in that VLAN, exactly matching the requirement.

Why this answer

The most appropriate configuration is to force the interface into access mode and assign it to VLAN 20. In practical terms, a normal user-facing switch port is supposed to carry one VLAN only. There is no reason to rely on dynamic trunk negotiation for a desktop or laptop connection. Explicit access-port configuration is cleaner, more predictable, and safer.

This is a common switching best-practice question. The wrong answers usually leave room for unwanted trunking behavior or move the interface into a completely different role. The right answer combines the correct port role with the correct VLAN membership.

Exam trap

Avoid assuming 'auto' mode is always safe; it can lead to unintended trunking.

Why the other options are wrong

B

This configuration makes the port a trunk port, which is used to carry multiple VLANs between switches, not for a single user PC. The 'switchport trunk native vlan 20' command sets the native VLAN for untagged traffic on the trunk, but the port still actively negotiates trunking via DTP, violating the requirement to not negotiate trunking.

C

The 'switchport mode dynamic desirable' command actively attempts to form a trunk with the connected device via DTP, which contradicts the requirement to not negotiate trunking. Additionally, 'switchport trunk allowed vlan 20' only restricts which VLANs are allowed on the trunk, but the port is still in trunking mode, not an access port.

D

The 'no switchport' command converts the Layer 2 switch port into a Layer 3 routed interface, which cannot be assigned to a VLAN. This configuration is used for routing between VLANs or connecting to routers, not for connecting a user PC to a specific VLAN.

129
MCQhard

Two switches should form an EtherChannel with LACP. One side is set to active and the other is set to passive. If the remaining interface settings match, what is the expected result?

A.The EtherChannel should form successfully.
B.The EtherChannel fails because both sides must be active.
C.The interfaces automatically become routed ports.
D.The switches delete the port-channel automatically.
AnswerA

In LACP, an interface configured as active actively sends LACP PDUs, while passive only responds to incoming PDUs. When one switch is active and the other passive, the active side's PDUs trigger the passive side to reply, allowing both devices to exchange port attributes and form a stable EtherChannel. The active/passive configuration is explicitly supported by the IEEE 802.3ad standard and is a common deployment for connecting to switches that do not support the active mode.

Why this answer

The EtherChannel should form successfully. In practical terms, active mode initiates LACP negotiation and passive mode listens and responds. Because one side is actively starting the negotiation, the bundle can come up if the interfaces also match in operational settings such as speed, duplex, switchport mode, and VLAN characteristics.

This is a classic LACP pairing question. Active/passive works. Passive/passive is the combination that usually fails to start the bundle.

Exam trap

Remember, LACP requires only one side to be active; passive mode will still respond.

Why the other options are wrong

B

LACP allows an active port to form a bundle with a passive port; the passive side simply waits for LACP packets from the active side. Therefore, both sides do not need to be active.

C

LACP mode does not change the Layer 2 or Layer 3 status of interfaces; it only controls the negotiation of EtherChannel bundling. Interfaces remain as switchports unless explicitly configured as routed ports.

D

LACP negotiation failure does not automatically delete the port-channel interface or its configuration. The port-channel remains, but the member ports will not bundle and will operate as individual ports.

130
MCQhard

A switch receives BPDUs on a user-facing port configured as an edge port, but instead of just blocking the port role it fully error-disables it. Which protection feature most likely explains that behavior?

AnswerA

BPDU Guard is a security feature designed for edge or access ports, typically used with PortFast. When a port configured with BPDU Guard receives any BPDU, it immediately transitions to the err-disabled state, because an unexpected BPDU indicates that a switch or bridge is connected to an end-user segment. This prevents the possibility of a bridging loop caused by a rogue switch and does not require manual intervention beyond the initial configuration, though recovery can be automatic if err-disable timeout is set.

Why this answer

BPDU Guard most likely explains that behavior. In practical terms, BPDU Guard is used to protect ports that are expected to face ordinary endpoints, not other switches. If BPDUs appear on such a port, the device treats that as a serious topology-policy violation and shuts the port down.

This is different from features that merely influence spanning-tree role choice without fully error-disabling the interface.

Exam trap

Be careful not to confuse BPDU Guard with other spanning tree protection features that do not disable ports upon receiving BPDUs.

Why the other options are wrong

B

Root guard does not error-disable a port; instead, it places the port into a root-inconsistent state if a superior BPDU is received, preventing the port from becoming a root port. It is used to enforce the root bridge location, not to disable ports upon BPDU reception.

C

Port security restricts the number of MAC addresses learned on a port and can error-disable the port if a violation occurs (e.g., too many MAC addresses). It does not react to BPDUs; its focus is on MAC address learning, not spanning-tree BPDUs.

D

DHCP snooping is a security feature that filters DHCP messages and can error-disable a port if a DHCP violation occurs (e.g., rogue DHCP server). It does not inspect or react to BPDUs, which are layer 2 spanning-tree frames.

131
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure a switch port for data and voice 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

Why this order

The correct order is: 1) Enter interface configuration mode, because all port-specific commands must be applied under the interface. 2) Set the port as an access port with 'switchport mode access'—a voice VLAN can only be assigned on an access port. 3) Assign the data VLAN with 'switchport access vlan' to ensure proper Layer 2 forwarding for data traffic. 4) Assign the voice VLAN with 'switchport voice vlan' so the IP phone's voice frames are tagged with the voice VLAN. 5) Enable PortFast with 'spanning-tree portfast' to immediately transition the port to forwarding, preventing DHCP timeouts for the phone and host.

132
MCQeasy

A switchport should allow only one learned MAC address and shut down if a different device is connected later. Which port security violation mode and limit combination best fits that goal?

A.maximum 1 with violation shutdown
B.maximum 10 with violation protect
C.maximum 1 with violation restrict and no logging
D.maximum unlimited with violation shutdown
AnswerA

This is the only configuration that meets the stated requirement exactly: port-security with a maximum of 1 restricts the interface to a single learned MAC address, and the shutdown violation mode immediately places the port into the err-disabled state if a second address is seen, effectively blocking all traffic on the port until an administrator manually re-enables it. Because both criteria—one learned MAC and automatic shutdown—are satisfied, this is the correct answer.

Why this answer

The usual setup is maximum 1 MAC address with violation mode shutdown. That way the port is disabled when an unauthorized device appears.

Exam trap

Be careful not to confuse the different port security violation modes. Only shutdown mode disables the port upon a violation.

Why the other options are wrong

B

The maximum limit of 10 MAC addresses is too high for the requirement of allowing only one learned MAC address. Additionally, protect mode drops frames from unknown MACs but does not shut down the port, so the port remains active even after a violation.

C

Restrict mode does not shut down the port; it only logs and drops frames from unknown MACs. The requirement explicitly states the port should shut down, which restrict does not achieve.

D

Setting the maximum to unlimited defeats the purpose of limiting MAC addresses to one. Even though violation mode is shutdown, the port will never trigger a violation because there is no limit, so it will never shut down due to port security.

133
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure an LACP EtherChannel on Cisco IOS-XE switches.

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 mode. Then create the port-channel interface. Next, configure the channel-group mode on each physical interface to active for LACP.

Finally, verify the configuration.

Exam trap

A common trap is to configure the channel-group mode on physical interfaces before creating the port-channel interface, or to forget that global configuration mode is the first step. Always remember the sequence: global config -> port-channel interface -> physical interface channel-group -> verification.

134
MCQhard

Users in VLAN 60 on switch SW2 cannot reach the default gateway located on switch SW1. The trunk between SW1 and SW2 is operational and allows VLAN 60. What is the most likely reason for this issue?

A.VLAN 60 does not exist locally on SW2.
B.The native VLAN must be changed to 60 on both switches.
C.VLAN 60 is not allowed on the trunk link.
D.The default gateway must be configured as a loopback on SW2.
AnswerA

This is the most likely reason: SW2 has not been created with VLAN 60, so it does not have a spanning-tree instance or a switch virtual interface for that VLAN. Even if the trunk port with SW1 allows VLAN 60 and receives tagged frames, those frames are discarded because the VLAN is not present in SW2's VLAN database. Consequently, users in VLAN 60 cannot communicate through SW2, and no access port or SVI can be assigned to that VLAN.

Why this answer

VLAN 60 has not been created locally on SW2, even though the trunk can carry its traffic. A switch never processes VLAN traffic for a VLAN it doesn't know about; it discards tagged frames from the trunk destined for that VLAN and prevents access ports from assigning frames to it. (A) is correct. (B) is incorrect because native VLAN configuration only affects untagged frames—changing it to 60 is unnecessary for tagged VLAN 60 traffic. (C) is incorrect because the trunk is already configured to allow VLAN 60, so trunk filtering isn't the problem. (D) is incorrect because a default gateway is simply an IP address on a router or Layer 3 switch interface (like SVIs) and does not require a loopback on SW2.

Exam trap

Don't assume trunk configuration alone resolves VLAN issues; ensure VLANs exist on all relevant switches.

Why the other options are wrong

B

Native VLAN configuration does not affect tagged VLAN 60 traffic—native VLAN only matters for untagged frames.

C

The trunk is stated to allow VLAN 60, so VLAN filtering is not the problem; a student might misread the premise.

D

The default gateway resides on SW1, not SW2; configuring a loopback on SW2 does not create a gateway for VLAN 60.

135
MCQhard

After a hub was connected to interface Gi0/10, the interface immediately entered errdisable state. The following syslog message was generated: '%PORT_SECURITY-2-PSECURE_VIOLATION: Security violation occurred on interface Gi0/10.' What is the strongest explanation for why Gi0/10 shut down?

A.Port security detected more MAC addresses than allowed on the interface.
B.The interface received a superior BPDU and became the root port.
C.The hub forced the interface to become a routed port.
D.DHCP snooping always shuts a port when a hub is attached.
AnswerA

Port security is explicitly configured to allow only one secure MAC address, and the violation message indicates that additional MAC addresses were seen on the interface. When a hub connects, multiple end devices share that single physical port, causing the switch to detect more source MACs than the configured maximum. This triggers the port-security violation and puts the interface into an error-disabled state, matching the exhibit.

Why this answer

The strongest explanation is a port-security violation caused by the switch seeing more secure MAC addresses than the interface allows. In practical terms, a hub or unmanaged device can cause multiple end hosts to appear behind one access port. If the interface is configured with a maximum of one secure MAC address, additional learned MACs trigger the violation action.

This is a realistic access-layer security scenario because the port does not fail randomly. It fails because the observed behavior violates the configured policy.

Exam trap

Remember that port security specifically deals with MAC address limits, not broadcast storms or spanning-tree issues.

Why the other options are wrong

B

The exhibit shows a port-security violation message, not an STP topology change. A superior BPDU would cause a root port election, not a port shutdown due to security policy.

C

Connecting a hub does not change the interface type; a switchport remains a Layer 2 interface unless explicitly configured with 'no switchport'. The exhibit shows a Layer 2 security violation, not a routed port conversion.

D

DHCP snooping does not automatically shut down a port when a hub is attached; it filters DHCP messages and can disable ports only if a DHCP server is detected on an untrusted port. The exhibit clearly shows a port-security violation message.

136
Drag & Dropmedium

What is the correct order of steps to capture and analyze traffic on IOS-XE using the embedded packet capture feature, and in Wireshark to isolate a Layer 2 or Layer 3 fault?

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 for embedded packet capture on IOS-XE is to first define the capture point with the desired interface and optional filter, then start the capture, stop it after capturing the needed traffic, and finally export the file for analysis in Wireshark. Option A accurately reflects this sequence. Option B fails because the capture must be defined before starting.

Option C fails because exporting should occur after stopping the capture. Option D fails because analysis is performed externally, not on the router.

Exam trap

Do not confuse the order of operations: you must define the capture point before starting, and you must stop the capture before exporting. Also, remember that analysis is done externally, not on the router itself.

137
MCQhard

Exhibit: Clients can see the corporate SSID but fail authentication after entering valid usernames and passwords. Which issue is the best explanation?

A.The AP is using the wrong RF channel
B.The RADIUS path or shared secret is failing
C.The SSID must be hidden for enterprise authentication
D.The clients need a voice VLAN assignment first
AnswerB

In WPA2-Enterprise, the access point acts as an 802.1X authenticator and forwards EAP credentials to a RADIUS server. If the shared secret is misconfigured or the RADIUS server is unreachable, the authentication exchange fails after the client associates, precisely matching the symptom of seeing the SSID but being unable to connect. This is the only option that directly impacts the authentication stage rather than association or RF visibility.

Why this answer

WPA2-Enterprise relies on 802.1X with a RADIUS server. If the RADIUS server is unreachable or the shared secret is wrong, users can see the SSID and attempt to authenticate, but the login process fails. Option A is incorrect because RF channel issues would cause connectivity problems, not authentication failures after association.

Option C is incorrect because hiding the SSID is irrelevant to enterprise authentication; the issue is server-side. Option D is incorrect because a voice VLAN is not required for standard client authentication and would not cause login failure.

Exam trap

Remember that WPA2-Enterprise relies on a RADIUS server. Authentication issues often stem from server communication problems, not client-side settings.

Why the other options are wrong

A

RF channel issues cause connectivity or performance problems, not authentication failures after a successful association.

C

Hiding the SSID does not affect the 802.1X authentication process; the failure is likely due to RADIUS communication.

D

Voice VLAN assignment is unrelated to client authentication; clients do not need a voice VLAN to authenticate.

138
MCQmedium

A port connected to an end-user PC should not send or expect VLAN tags from the endpoint. Which interface type is appropriate on the switch?

C.Routed port
D.Port-channel interface
AnswerA

An access port is correct because it carries traffic for exactly one VLAN and forwards untagged frames, which is exactly what a PC's NIC expects. PCs do not generate 802.1Q VLAN tags, so an access port's behavior of stripping and expecting untagged data aligns with the end-device's native Ethernet operation. Furthermore, access ports do not transmit DTP (Dynamic Trunking Protocol) frames, preventing any unwanted trunk negotiation toward the PC.

Why this answer

The appropriate interface type is an access port. In plain language, a normal user PC is expected to connect to one VLAN and send ordinary untagged Ethernet frames. The switch associates that traffic with the configured access VLAN.

This is different from a trunk, which is designed to carry multiple VLANs and commonly uses tagging to preserve VLAN identity across the link. Routed ports are Layer 3 interfaces used for routing between VLANs, not for attaching a single end-user PC. Port-channel interfaces aggregate multiple physical links for redundancy and bandwidth, but they do not determine whether VLAN tagging is used; the underlying port mode (access or trunk) still applies.

Therefore, access port is the only correct choice for an untagged, single-VLAN end-device connection.

Exam trap

Don't confuse the need for VLANs with the need for VLAN tagging. Access ports handle untagged traffic for single VLANs.

Why the other options are wrong

B

A trunk port is designed to carry traffic for multiple VLANs using 802.1Q tagging, which is not expected from a standard PC. Using a trunk port for a PC would cause the switch to expect tagged frames, leading to communication failures.

C

A routed port is a Layer 3 interface used for routing between VLANs or connecting to routers, not for connecting end-user PCs. It does not operate as a Layer 2 switchport and would not handle VLAN tagging as required.

D

A port-channel interface is a logical bundling of multiple physical links for increased bandwidth and redundancy, not a single connection to an end-user PC. It is used between switches or to servers, not for typical PC access.

139
PBQeasy

You are connected to SW1 via the console. SW1 is a Layer 2 switch with an access port G0/1 connected to a server. The network administrator has noticed that the server is sending BPDUs, which could cause network instability. You need to configure PortFast and BPDU Guard on port G0/1 to prevent BPDU-related issues and ensure the port transitions to forwarding state immediately.

Network Topology
G0/1ServerSW1

Hints

  • PortFast enables immediate transition from blocking to forwarding state.
  • BPDU Guard disables the port if a BPDU is received.
  • These features are typically applied to access ports connected to end devices.
A.interface G0/1 spanning-tree portfast spanning-tree bpduguard enable
B.interface G0/1 spanning-tree portfast spanning-tree guard root
C.interface G0/1 spanning-tree portfast spanning-tree bpdufilter enable
D.interface G0/1 spanning-tree portfast spanning-tree bpduguard default
AnswerA
solution
! SW1
interface GigabitEthernet0/1
spanning-tree portfast
spanning-tree bpduguard enable

Why this answer

PortFast allows an access port to bypass STP listening/learning states, providing immediate connectivity. BPDU Guard protects the network by shutting down the port if a BPDU is received, preventing potential loops from unauthorized switches.

Exam trap

Cisco exams often test the exact syntax for STP features. Remember that BPDU Guard uses 'enable' at the interface level, while BPDU Filter uses 'enable' as well. Root Guard uses 'guard root'.

Do not confuse these or use global commands on interfaces.

Why the other options are wrong

B

The specific factual error is confusing Root Guard with BPDU Guard. Root Guard is used to enforce the root bridge position, not to protect against BPDUs.

C

The specific factual error is that BPDU Filter silently drops BPDUs instead of taking action, which can allow loops to form if an unauthorized switch is connected.

D

The specific factual error is using the global configuration command on an interface. The global command enables BPDU Guard on all PortFast-enabled ports, but the question asks to configure it on a specific port.

140
PBQhard

You are connected to R1. Configure inter-VLAN routing on R1 using router-on-a-stick so that hosts in VLAN 10 (192.168.10.0/24) and VLAN 20 (192.168.20.0/24) can communicate. The switch SW1 is already configured with VLANs and trunking, but R1's current configuration prevents traffic. Identify and fix the issues.

Network Topology
G0/0trunkR1SW1

Hints

  • Check if the physical interface is administratively down.
  • Verify that the trunk is allowing VLANs 10 and 20.
  • Ensure 'ip routing' is enabled (it is by default).
A.Enable the physical interface with the 'no shutdown' command on R1.
B.Change the encapsulation on the subinterfaces to use dot1Q with native VLAN 10 and 20 respectively.
C.Enable IP routing globally with the 'ip routing' command on R1.
D.Remove the 'no shutdown' from the subinterfaces and apply it only to the physical interface.
AnswerA
solution
! R1
interface GigabitEthernet0/0
no shutdown
exit
show interfaces trunk

Why this answer

The issue was that the physical interface GigabitEthernet0/0 on R1 was administratively down, causing all subinterfaces for VLANs 10 and 20 to be in a down state. Enabling it with 'no shutdown' brings the trunk up, allowing inter-VLAN routing because the switch already has trunking configured. The other options are incorrect because they suggest steps that are either already in place (IP routing) or not needed (changing encapsulation or moving no shutdown to subinterfaces).

Exam trap

A common mistake is overlooking that router-on-a-stick requires the physical interface to be administratively up, as subinterfaces cannot function independently.

Why the other options are wrong

B

Changing encapsulation is unnecessary because the subinterfaces already use the correct dot1Q encapsulation for VLANs 10 and 20.

C

The 'ip routing' command is already enabled by default on routers, and global routing is not the problem here.

D

Subinterfaces do not support a 'no shutdown' command; their operational state is determined solely by the physical interface.

141
MCQmedium

Why is BPDU Guard commonly enabled on PortFast-enabled access ports?

A.To make STP root election happen faster
B.To disable STP permanently on access ports
C.To err-disable a port if it receives unexpected BPDUs
D.To allow only one MAC address on the access port
AnswerC

BPDU Guard is a protective feature used with PortFast on access ports to prevent loops from unauthorized BPDUs. If the port receives any BPDU, which should not occur on an end-node connection, the switch immediately err-disables the interface to stop potential bridging loops. This safeguards the network from misconfigured or malicious devices.

Why this answer

PortFast ports are meant for end devices, not for switches. BPDU Guard protects the LAN by shutting down a PortFast port that unexpectedly starts receiving BPDUs, which usually means an unauthorized switch was connected.

Exam trap

Don't confuse BPDU Guard with PortFast or BPDU filtering; each has distinct roles.

Why the other options are wrong

A

BPDU Guard is a security feature that err-disables a port upon receiving BPDUs; it does not accelerate root election. Root election speed is influenced by STP timers and bridge priorities, not BPDU Guard.

B

BPDU Guard does not disable STP permanently; it only reacts to BPDU reception by err-disabling the port. STP remains active on other ports, and the port can be re-enabled after the violation is resolved.

D

Limiting MAC addresses on a port is the function of port security, not BPDU Guard. BPDU Guard specifically monitors for BPDU frames and takes action if any are received.

142
Drag & Dropmedium

Drag and drop the following steps into the correct order to configure inter-VLAN routing using a router-on-a-stick topology.

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

Why this order

Inter-VLAN routing via router-on-a-stick requires creating VLANs on the switch, placing access ports in those VLANs, configuring a trunk to the router with the correct native VLAN to avoid mismatch, enabling the physical router interface, and then defining subinterfaces per VLAN with 802.1Q encapsulation and IP addresses. This ensures traffic from different VLANs can be routed.

143
MCQhard

A trunk link has a native VLAN mismatch between two switches. What is the most likely result?

A.All VLANs except the native VLAN stop forwarding immediately.
B.Untagged frames can be interpreted as belonging to different VLANs on each switch.
C.The trunk automatically converts to an access port.
D.STP is disabled on the trunk until the mismatch is corrected.
AnswerB

With a native VLAN mismatch, each switch places untagged 802.1Q frames into its locally configured native VLAN. For example, if Switch A's native VLAN is 10 and Switch B's is 20, a single untagged frame will be associated with VLAN 10 on one side and VLAN 20 on the other, effectively crossing broadcast domains and potentially exposing traffic to the wrong VLAN. This misclassification can lead to security breaches, routing loops, or connectivity anomalies because VLAN membership is not preserved end-to-end.

Why this answer

Untagged traffic may be placed into different VLANs on each side of the trunk, causing traffic leakage or connectivity problems.

Exam trap

Be careful not to confuse native VLAN mismatches with issues that affect tagged traffic or automatic switch behavior.

Why the other options are wrong

A

A native VLAN mismatch does not cause all other VLANs to stop forwarding. The trunk continues to forward frames for all VLANs, but untagged frames (native VLAN) are miscommunicated.

C

A trunk port does not automatically convert to an access port due to a native VLAN mismatch. The trunk remains operational, but the native VLAN mismatch causes problems for untagged traffic.

D

STP continues to run normally on the trunk link despite a native VLAN mismatch. The mismatch does not disable STP; it only affects the handling of untagged frames.

144
Drag & Dropmedium

A network troubleshooter is using Cisco IOS-XE's embedded packet capture feature to capture traffic on an interface and then analyze it in Wireshark to isolate a Layer 2 or Layer 3 fault. Which of the following sequences represents the correct order of steps?

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 workflow is to first define the capture point (interface and any filters), then start the capture, stop it when sufficient data is collected, export the captured packets to a file, and finally open that file in Wireshark for analysis. Starting the capture before defining the point, exporting before stopping, or defining the point after stopping all result in an invalid or incomplete capture process.

Exam trap

Remember that the capture point must be defined before starting the capture, and the capture must be stopped before exporting. Do not confuse the order of these steps.

145
Multi-Selectmedium

Which two statements accurately describe why organizations use separate employee and guest WLANs?

Select 2 answers
A.They allow different access policies and trust boundaries for different user groups.
B.They help isolate guest access from internal corporate resources.
C.They eliminate the need for wireless security.
D.They make all roaming problems disappear automatically.
E.They replace the need for VLANs or policy controls behind the scenes.
AnswersA, B

Separate WLANs map to distinct security domains, enabling administrators to enforce role-based policies such as 802.1X authentication for employees and PSK access for guests. This segmentation establishes clear trust boundaries, so that device type, user role, or location can determine which network resources are reachable. Without multiple WLANs, all clients might share the same Layer 2 domain, making it impossible to apply differentiated security controls.

Why this answer

Organizations use separate WLANs because different user groups usually require different trust levels, policies, and access rights. In practical terms, employees may need access to internal business systems, while guests usually need a more limited and isolated experience. Separate WLANs make that segmentation and policy enforcement easier.

This is a design and security decision, not just a naming preference.

Exam trap

Avoid assuming that separate WLANs are used for performance improvements or marketing purposes; focus on security and access control.

Why the other options are wrong

C

Separate WLANs do not eliminate the need for wireless security; both employee and guest WLANs require encryption (e.g., WPA2/WPA3) and authentication mechanisms to protect data in transit and prevent unauthorized access.

D

Roaming problems, such as handoff delays or authentication re-requirements, are not automatically resolved by having separate WLANs; they depend on factors like controller configuration, AP placement, and roaming protocols (e.g., 802.11r).

E

Separate WLANs do not replace the need for VLANs or policy controls; in fact, they often rely on VLANs to segregate traffic and on additional policies (e.g., ACLs, firewall rules) to enforce access restrictions between the WLANs and the network.

146
MCQhard

An administrator connects a new access-layer switch to a distribution switch. The link comes up but remains in a blocking state and does not forward frames. The administrator issues the show command shown in the exhibit. What is the most likely reason the link is blocked?

A.BPDU Guard is enabled on the port, and the new switch's BPDUs caused the port to enter err-disable state.
B.Loop Guard is enabled, and the port has stopped receiving BPDUs, leading to a loop-inconsistent state.
C.Root Guard is configured on the port, and the new access switch is sending superior BPDUs, triggering a root-inconsistent state.
D.The port is configured with PortFast, and the new switch's BPDU triggered a loop, causing the port to err-disable.
AnswerC

Root Guard is the mechanism that enforces the root bridge position by transitioning a port to the 'root-inconsistent' state when a superior BPDU (lower bridge ID) arrives, effectively blocking the port. Because the new access switch is sending superior BPDUs, the port has been placed in a blocked state to prevent it from becoming the root port and usurping the root bridge. The 'show spanning-tree inconsistentports' output confirms this condition, and the port will automatically recover once the superior BPDUs cease, which is consistent with the exhibit.

Why this answer

The link is blocked because Root Guard is configured on the distribution switch port. When the new access-layer switch sends superior BPDUs (with a lower bridge priority), Root Guard transitions the port to a root-inconsistent (blocking) state to protect the current root bridge from being usurped. This prevents the new switch from becoming the root bridge, which would disrupt the spanning-tree topology.

Exam trap

Cisco often tests the distinction between err-disable states (BPDU Guard) and blocking states (Root Guard, Loop Guard), so the trap here is assuming any BPDU-related protection causes err-disable, when Root Guard specifically causes a blocking state without err-disable.

Why the other options are wrong

A

BPDU Guard results in err-disable, which is not reflected in the show spanning-tree inconsistentports output. The exhibit clearly shows Root Inconsistent, indicating Root Guard, not BPDU Guard.

B

Loop Guard creates a loop-inconsistent listing, not root-inconsistent. The command output explicitly indicates Root Inconsistent, ruling out Loop Guard.

D

Without BPDU Guard, PortFast does not react to BPDUs with a blocking state. The exhibit's root-inconsistent inconsistency is specific to Root Guard, not PortFast or BPDU Guard.

147
MCQmedium

After a switch replacement, users in VLAN 30 cannot reach devices in other VLANs. The replacement switch has a trunk link to the distribution switch that shows as up/up. What is the most likely cause?

A.The native VLAN must be changed to 30
B.VLAN 30 is not permitted on the trunk link
C.The uplink should be configured as an access port
D.STP must be disabled on VLAN 30
AnswerB

The trunk allowed list controls which VLANs traverse the link, and without an explicit 'allowed vlan add 30' statement, frames belonging to VLAN 30 are discarded at the trunk. Because the access switch and distribution switch only carry permitted VLANs, VLAN 30 has no path to the rest of the network. This exactly matches the symptom that only VLAN 30 suffers while other VLANs work normally on the same uplink.

Why this answer

The trunk is up, but VLAN 30 is not allowed on it. Traffic from that VLAN never crosses the uplink, so inter-VLAN reachability fails for users in VLAN 30 even though the local access ports may still look fine.

Exam trap

Ensure you distinguish between management settings and VLAN configuration. Focus on trunk settings when inter-VLAN issues arise.

Why the other options are wrong

A

Changing the native VLAN to 30 would not resolve the issue because the native VLAN is used for untagged traffic on a trunk, and the problem is that VLAN 30 traffic is not being allowed at all. Additionally, native VLAN mismatch can cause connectivity issues, but it does not specifically prevent only VLAN 30 from reaching other VLANs.

C

Configuring the uplink as an access port would place it in a single VLAN, preventing traffic from multiple VLANs (including VLAN 30) from traversing the link. Since the switch needs to carry traffic for multiple VLANs, the uplink must remain a trunk port.

D

Disabling STP on VLAN 30 would be dangerous as it could cause bridging loops and network instability. Moreover, STP does not control whether a VLAN is allowed on a trunk; it only prevents loops. The issue is a missing VLAN in the trunk allowed list, not a spanning-tree problem.

148
MCQmedium

A switch administrator enters the following commands on interface GigabitEthernet1/0/10: interface g1/0/10 switchport mode access switchport access vlan 30 spanning-tree portfast spanning-tree bpduguard enable A user connects a small managed switch to this port, and the access port immediately changes to an err-disabled state. Which feature caused the port to shut down?

C.Access VLAN 30 assignment
D.The interface being in access mode
AnswerB

Correct. BPDU Guard is correct because it is specifically designed to shut down an edge port that should not receive BPDUs. In plain terms, the switch sees evidence that another switch was attached and decides to protect the topology by disabling the port instead of allowing a possible loop or unexpected spanning-tree participation.

Why this answer

BPDU Guard is the feature that caused the shutdown. This question is really about separating two features that are often configured together on user-facing ports: PortFast and BPDU Guard. PortFast helps an edge port come up quickly, which is useful for PCs and phones.

BPDU Guard adds protection by watching for BPDUs on that same port. If a switch is connected where only an end device should exist, the newly connected switch may send BPDUs. The local switch interprets that as a topology risk and disables the port to protect the Layer 2 network.

The clues are the err-disabled state and the fact that another switch was connected. VLAN assignment and access mode are normal here and do not explain the shutdown.

Exam trap

Remember that BPDU Guard, not PortFast, causes a port to shut down when BPDUs are received. PortFast only affects port transition speed.

Why the other options are wrong

A

PortFast is a feature that allows a port to transition immediately to the forwarding state, bypassing the usual spanning-tree listening and learning phases. It does not cause a port to shut down or enter an err-disabled state; it only speeds up convergence for end-user devices.

C

Assigning an access VLAN (VLAN 30) simply places the port into a specific broadcast domain for user traffic. It has no mechanism to detect or react to BPDUs, and it does not cause a port to enter an err-disabled state. The port would remain operational regardless of the VLAN assignment.

D

Configuring a port as an access port is a standard practice for connecting end devices. It does not inherently cause any shutdown or err-disabled condition. The port remains up and forwarding traffic unless another feature, such as BPDU Guard, triggers a protective action.

149
Multi-Selectmedium

Which TWO statements correctly describe the configuration and verification of EtherChannel with LACP?

Select 2 answers
A.LACP uses the 'active' and 'passive' modes to negotiate an EtherChannel.
B.The 'show etherchannel summary' command displays the channel group number, port-channel interface, member ports, and their status.
C.LACP uses the 'auto' and 'desirable' modes to negotiate an EtherChannel.
D.The 'show etherchannel summary' command shows the LACP system priority for each channel.
E.An EtherChannel can be formed only if all member ports use the same LACP mode.
AnswersA, B

This statement is correct. LACP negotiation relies on two modes: 'active' and 'passive'. An interface in 'active' mode actively sends LACP packets to initiate the link aggregation, while one in 'passive' mode waits for a response and only sends packets after receiving them. For an EtherChannel to form, at least one side must be 'active'; if both sides are 'passive', the channel will not come up because no negotiation is initiated.

Why this answer

LACP (IEEE 802.3ad) uses 'active' and 'passive' modes to negotiate an EtherChannel. Option B is correct because the 'show etherchannel summary' command displays the channel group number, port-channel interface, member ports, and their status flags (e.g., P for in port-channel, S for suspended). Option C is incorrect because 'auto' and 'desirable' are PAgP modes, not LACP modes.

Option D is incorrect because 'show etherchannel summary' does not show LACP system priority; that is displayed with 'show lacp sys-id' or 'show etherchannel detail'. Option E is incorrect because an EtherChannel can be formed with mismatched LACP modes as long as at least one side is 'active'; for example, 'active' + 'passive' works.

Exam trap

Cisco often tests the distinction between LACP modes ('active'/'passive') and PAgP modes ('auto'/'desirable'), and candidates frequently confuse which protocol uses which set of modes.

Why the other options are wrong

C

LACP does not use 'auto' and 'desirable' modes; those are PAgP modes.

D

The 'show etherchannel summary' command does not display LACP system priority; that is shown via 'show lacp sys-id' or 'show etherchannel detail'.

E

An EtherChannel can be formed even if member ports use different LACP modes (e.g., active and passive), as long as at least one side is active.

150
Multi-Selectmedium

Which two statements accurately describe WPA2 and WPA3 in wireless security?

Select 2 answers
A.Both are wireless security standards used to help protect WLAN access and traffic.
B.WPA3 is the newer standard relative to WPA2.
C.Both are names for specific 802.11 radio frequencies.
D.WPA2 and WPA3 are types of trunk ports.
E.WPA3 eliminates the need for SSIDs.
AnswersA, B

WPA2 and WPA3 are security protocols that provide authentication and encryption for wireless LANs. WPA2 relies on AES-CCMP for data confidentiality, while WPA3 uses AES-GCMP (with 128-bit keys) and mandates Protected Management Frames to strengthen integrity. They both secure the communications between a wireless client and an access point, thereby protecting WLAN access and traffic from eavesdropping, tampering, and unauthorized use.

Why this answer

WPA2 and WPA3 are wireless security standards used to protect WLAN access and traffic. In practical terms, both are associated with securing wireless communication, but WPA3 is generally positioned as the newer standard with security improvements over WPA2. The key idea at CCNA level is recognizing them as WLAN security standards rather than confusing them with SSIDs, controllers, or radio bands.

You do not need deep protocol internals here. You need the role and relative positioning right.

Exam trap

Avoid assuming WPA3 is limited to specific frequency bands or that WPA2 offers superior security features.

Why the other options are wrong

C

WPA2 and WPA3 are security protocols, not radio frequencies. 802.11 radio frequencies refer to bands like 2.4 GHz and 5 GHz, which are unrelated to security standards.

D

Trunk ports are a concept in switched networks for carrying multiple VLANs, typically using 802.1Q tagging. WPA2 and WPA3 have nothing to do with switch port configuration.

E

WPA3 does not eliminate the need for SSIDs; SSIDs are still required to identify and differentiate wireless networks. WPA3 focuses on authentication and encryption, not network identification.

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