Question 1,373 of 1,819
Switching and Network AccesshardTroubleshootingObjective-mapped

CCNA Switching and Network Access Practice Question

This 200-301 practice question tests your understanding of switching and network access. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.

Network Topology
Gi0/1-Gi0/2Gi0/1-Gi0/2EtherChannelSW1SW2

You are connected to SW1. Configure an LACP EtherChannel between SW1 and SW2 using ports GigabitEthernet0/1 and GigabitEthernet0/2. Set the channel-group mode to active on both sides. The port-channel interface should be configured as a trunk allowing VLANs 10, 20, and 30. Initially, the EtherChannel fails to form due to mismatched speed/duplex on one link. Identify and correct the issue, then verify the channel is up and operational.

Question 1hardTroubleshooting
Open the full VLAN trunking answer →
Network Topology
+interface GigabitEthernet0/1switchport mode trunkswitchport trunk allowed vlan 10,20,30speed 1000duplex fullchannel-group 1 mode activeinterface GigabitEthernet0/2speed 100duplex halfinterface Port-channel1SW1#show etherchannel summaryH - Hot-standby (LACP only)Number of aggregators: 1Group Port-channel Protocol Ports1 Po1(SD) LACP Gi0/1(I) Gi0/2(I)

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

Change speed and duplex on Gi0/2 to 1000 and full, then verify with 'show etherchannel summary'.

The EtherChannel fails because GigabitEthernet0/2 has speed 100 and duplex half, while GigabitEthernet0/1 has speed 1000 and duplex full. LACP requires all member ports to have identical speed and duplex settings. To resolve, change the speed and duplex on Gi0/2 to match Gi0/1: 'speed 1000' and 'duplex full'. After correction, the channel will bundle. Verify with 'show etherchannel summary' to see both ports in the 'P' (bundled) 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.

  • Change speed and duplex on Gi0/2 to 1000 and full, then verify with 'show etherchannel summary'.

    Why this is correct

    This is correct because LACP requires all member ports to have identical speed and duplex settings. Gi0/2 had speed 100 and duplex half, while Gi0/1 had speed 1000 and duplex full. Changing Gi0/2 to match resolves the mismatch, allowing the EtherChannel to bundle. Verification with 'show etherchannel summary' shows both ports in the 'P' (bundled) state.

    Related concept

    Access ports place end devices into a single VLAN.

  • Change the channel-group mode on Gi0/2 to passive, then verify with 'show etherchannel summary'.

    Why it's wrong here

    This is incorrect because the mode mismatch (active vs passive) is not the issue here; both sides are already set to active. Changing Gi0/2 to passive would create a mode mismatch, preventing the channel from forming. The actual problem is speed/duplex mismatch.

  • Change the allowed VLANs on the port-channel to include only VLAN 1, then verify with 'show etherchannel summary'.

    Why it's wrong here

    This is incorrect because VLAN configuration does not affect EtherChannel formation; it only affects traffic forwarding. The issue is at Layer 1 (speed/duplex). Changing allowed VLANs will not resolve the mismatch.

  • Change the port-channel interface to access mode, then verify with 'show etherchannel summary'.

    Why it's wrong here

    This is incorrect because the port-channel interface mode (trunk vs access) does not affect EtherChannel formation. The issue is speed/duplex mismatch. Changing to access mode would not fix the underlying Layer 1 problem.

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.

Change speed and duplex on Gi0/2 to 1000 and full, then verify with 'show etherchannel summary'.Correct answer

Why this is correct

This is correct because LACP requires all member ports to have identical speed and duplex settings. Gi0/2 had speed 100 and duplex half, while Gi0/1 had speed 1000 and duplex full. Changing Gi0/2 to match resolves the mismatch, allowing the EtherChannel to bundle. Verification with 'show etherchannel summary' shows both ports in the 'P' (bundled) state.

Change the channel-group mode on Gi0/2 to passive, then verify with 'show etherchannel summary'.Wrong answer — click to see why

Why this is wrong here

The specific factual error is that LACP modes must be compatible (active-active or active-passive), but the question states both sides are active, so mode is not the issue.

Why candidates choose this

Candidates might think that LACP mode mismatch is the cause, especially if they recall that one side must be active and the other passive in some configurations.

Change the allowed VLANs on the port-channel to include only VLAN 1, then verify with 'show etherchannel summary'.Wrong answer — click to see why

Why this is wrong here

The specific factual error is that VLAN settings are irrelevant to the physical bundling of ports in an EtherChannel.

Why candidates choose this

Candidates might confuse trunk configuration requirements with EtherChannel prerequisites, thinking that VLAN mismatches can prevent channel formation.

Change the port-channel interface to access mode, then verify with 'show etherchannel summary'.Wrong answer — click to see why

Why this is wrong here

The specific factual error is that interface mode is a Layer 2 property unrelated to the physical bundling process.

Why candidates choose this

Candidates might think that trunk mode requires additional configuration that could cause issues, or they might confuse the port-channel interface configuration with the physical port settings.

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.

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: Change speed and duplex on Gi0/2 to 1000 and full, then verify with 'show etherchannel summary'. — The EtherChannel fails because GigabitEthernet0/2 has speed 100 and duplex half, while GigabitEthernet0/1 has speed 1000 and duplex full. LACP requires all member ports to have identical speed and duplex settings. To resolve, change the speed and duplex on Gi0/2 to match Gi0/1: 'speed 1000' and 'duplex full'. After correction, the channel will bundle. Verify with 'show etherchannel summary' to see both ports in the 'P' (bundled) 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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