Question 374 of 1,819
Switching and Network AccesshardTroubleshootingObjective-mapped

Quick Answer

The answer is to configure `errdisable recovery cause bpduguard` and `errdisable recovery interval 300` globally on the switch. This is correct because BPDU Guard places a PortFast-enabled access port into an err-disabled state upon receiving an unexpected BPDU, and automatic recovery requires explicitly enabling the cause and setting a timer—without the `cause bpduguard` command, the interface will remain down indefinitely even with an interval configured. On the CCNA 200-301 v2 exam, this scenario tests your understanding of spanning-tree security features and the global errdisable recovery mechanism, often appearing as a configuration or troubleshooting item where a candidate must distinguish between enabling recovery per cause versus setting the timer. A common trap is forgetting that `errdisable recovery cause bpduguard` is mandatory; the interval alone does nothing without the cause enabled. Memory tip: think “cause before interval”—you must tell the switch *what* to recover before telling it *when* to recover.

CCNA Switching and Network Access Practice Question

This 200-301 practice question tests your understanding of switching and network access. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Exhibit

R1# show interfaces status
Port      Name   Status       Vlan    Duplex  Speed Type
Gi0/0            connected    routed    full   1000  SFP
Gi0/1            err-disabled 10       auto   auto  10/100/1000BaseTX
Gi0/2            notconnect   10       auto   auto  10/100/1000BaseTX
Gi0/3            connected    routed    full   1000  SFP

R1# show running-config | section interface GigabitEthernet0/1
interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
 spanning-tree bpduguard enable
 spanning-tree portfast

R1# show running-config | include errdisable

R1# show spanning-tree vlan 10
  VLAN0010
    Spanning tree enabled protocol rstp
    Root ID    Priority    24586
               Address     aaaa.bbbb.cccc
               This bridge is the root
    Bridge ID  Priority    24586  (priority 24576 sys-id-ext 10)
               Address     aaaa.bbbb.cccc
    Interface        Role Sts Cost      Prio.Nbr Type
    Gi0/1            Desg BKN*4         128.2    P2p *BPDU_Guard
    Gi0/2            Desg BLK 4         128.3    P2p

*BPDU_Guard: err-disabled

You are connected to R1, a multilayer switch acting as the root bridge for VLAN 10. The network has experienced a loop, and interface GigabitEthernet0/1 on R1 is currently in err-disabled state due to a BPDU guard violation. Configure the switch to recover automatically from err-disable state after 300 seconds, then verify that the interface comes back up.

Question 1hardTroubleshooting
Open the full VLAN trunking answer →

Exhibit

R1# show interfaces status
Port      Name   Status       Vlan    Duplex  Speed Type
Gi0/0            connected    routed    full   1000  SFP
Gi0/1            err-disabled 10       auto   auto  10/100/1000BaseTX
Gi0/2            notconnect   10       auto   auto  10/100/1000BaseTX
Gi0/3            connected    routed    full   1000  SFP

R1# show running-config | section interface GigabitEthernet0/1
interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
 spanning-tree bpduguard enable
 spanning-tree portfast

R1# show running-config | include errdisable

R1# show spanning-tree vlan 10
  VLAN0010
    Spanning tree enabled protocol rstp
    Root ID    Priority    24586
               Address     aaaa.bbbb.cccc
               This bridge is the root
    Bridge ID  Priority    24586  (priority 24576 sys-id-ext 10)
               Address     aaaa.bbbb.cccc
    Interface        Role Sts Cost      Prio.Nbr Type
    Gi0/1            Desg BKN*4         128.2    P2p *BPDU_Guard
    Gi0/2            Desg BLK 4         128.3    P2p

*BPDU_Guard: err-disabled

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Configure 'errdisable recovery cause bpduguard' and 'errdisable recovery interval 300' globally, then verify with 'show interfaces status'.

The interface Gi0/1 is in err-disabled state because BPDU Guard detected an unexpected BPDU on a PortFast-enabled access port. To recover automatically, configure errdisable recovery cause bpduguard and set the recovery interval to 300 seconds with errdisable recovery interval 300. After applying these commands, the interface will automatically come out of err-disable state after 300 seconds. The blocking port on Gi0/2 is expected because R1 is the root bridge and Gi0/2 is an alternate port providing redundancy; no action is needed for that blocking state.

Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Configure 'errdisable recovery cause bpduguard' and 'errdisable recovery interval 300' globally, then verify with 'show interfaces status'.

    Why this is correct

    This is correct because the errdisable recovery cause bpduguard command enables automatic recovery for interfaces disabled by BPDU guard, and the errdisable recovery interval 300 sets the recovery timer to 300 seconds. The 'show interfaces status' command verifies that the interface returns to up/up state.

    Related concept

    Access ports place end devices into a single VLAN.

  • Configure 'spanning-tree portfast bpduguard default' and 'errdisable recovery interval 300' globally, then verify with 'show spanning-tree'.

    Why it's wrong here

    This is incorrect because 'spanning-tree portfast bpduguard default' enables BPDU guard on all PortFast-enabled ports, but it does not enable automatic recovery from err-disable state. The 'show spanning-tree' command does not show errdisable recovery status.

  • Configure 'errdisable recovery cause all' and 'errdisable recovery interval 300' globally, then verify with 'show errdisable recovery'.

    Why it's wrong here

    This is incorrect because 'errdisable recovery cause all' enables recovery for all errdisable causes, which is overly broad and not recommended. The question specifically asks to recover from BPDU guard violation, so using 'cause bpduguard' is more precise. While 'show errdisable recovery' is a valid verification command, the configuration is not optimal.

  • Configure 'errdisable recovery cause bpduguard' and 'errdisable recovery interval 300' on interface GigabitEthernet0/1, then verify with 'show interfaces GigabitEthernet0/1'.

    Why it's wrong here

    This is incorrect because errdisable recovery commands are configured globally, not on a per-interface basis. Applying them under the interface will result in an error. The 'show interfaces' command can show the interface status, but the configuration is invalid.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.

Configure 'errdisable recovery cause bpduguard' and 'errdisable recovery interval 300' globally, then verify with 'show interfaces status'.Correct answer

Why this is correct

This is correct because the errdisable recovery cause bpduguard command enables automatic recovery for interfaces disabled by BPDU guard, and the errdisable recovery interval 300 sets the recovery timer to 300 seconds. The 'show interfaces status' command verifies that the interface returns to up/up state.

Configure 'spanning-tree portfast bpduguard default' and 'errdisable recovery interval 300' globally, then verify with 'show spanning-tree'.Wrong answer — click to see why

Why this is wrong here

The specific factual error: 'spanning-tree portfast bpduguard default' enables BPDU guard, not recovery. Recovery requires 'errdisable recovery cause bpduguard'.

Why candidates choose this

Candidates pick this because they confuse enabling BPDU guard with configuring recovery, and they may think 'show spanning-tree' shows errdisable status.

Configure 'errdisable recovery cause all' and 'errdisable recovery interval 300' globally, then verify with 'show errdisable recovery'.Wrong answer — click to see why

Why this is wrong here

The specific factual error: Using 'cause all' is not the best practice; the question implies a specific cause. Also, the verification command is correct but the configuration is not precise.

Why candidates choose this

Candidates pick this because 'cause all' seems like a catch-all solution, and they may not realize that specific recovery is preferred.

Configure 'errdisable recovery cause bpduguard' and 'errdisable recovery interval 300' on interface GigabitEthernet0/1, then verify with 'show interfaces GigabitEthernet0/1'.Wrong answer — click to see why

Why this is wrong here

The specific factual error: errdisable recovery is a global configuration command, not interface-specific.

Why candidates choose this

Candidates pick this because they think recovery settings should be applied directly to the affected interface, similar to other interface-specific commands.

Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Common exam traps

Common exam trap: an active trunk can still block the VLAN you need

A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.

Trap categories for this question

  • Command / output trap

    This is incorrect because 'spanning-tree portfast bpduguard default' enables BPDU guard on all PortFast-enabled ports, but it does not enable automatic recovery from err-disable state. The 'show spanning-tree' command does not show errdisable recovery status.

Detailed technical explanation

How to think about this question

VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.

KKey Concepts to Remember

  • Access ports place end devices into a single VLAN.
  • Trunk ports carry multiple VLANs between switches.
  • Allowed VLAN lists decide which VLANs can cross a trunk.
  • Native VLAN mismatch can create confusing symptoms.

TExam Day Tips

  • Use show vlan brief to verify access VLANs.
  • Use show interfaces trunk to verify trunk state and allowed VLANs.
  • Do not treat every same-VLAN issue as a routing problem.

Key takeaway

A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Real-world example

How this comes up in practice

A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.

What to study next

Got this wrong? Here's your next step.

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.

Related practice questions

Related 200-301 practice-question pages

Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

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FAQ

Questions learners often ask

What does this 200-301 question test?

Switching and Network Access — This question tests Switching and Network Access — Access ports place end devices into a single VLAN..

What is the correct answer to this question?

The correct answer is: Configure 'errdisable recovery cause bpduguard' and 'errdisable recovery interval 300' globally, then verify with 'show interfaces status'. — The interface Gi0/1 is in err-disabled state because BPDU Guard detected an unexpected BPDU on a PortFast-enabled access port. To recover automatically, configure errdisable recovery cause bpduguard and set the recovery interval to 300 seconds with errdisable recovery interval 300. After applying these commands, the interface will automatically come out of err-disable state after 300 seconds. The blocking port on Gi0/2 is expected because R1 is the root bridge and Gi0/2 is an alternate port providing redundancy; no action is needed for that blocking state.

What should I do if I get this 200-301 question wrong?

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.

What is the key concept behind this question?

Access ports place end devices into a single VLAN.

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Last reviewed: Jun 6, 2026

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