- A
On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 10,20,30.
This resolves the speed/duplex mismatch by matching SW1's settings and adds VLAN 30 to the allowed list, meeting the trunk requirements. LACP requires consistent speed and duplex across all member links.
- B
On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 100, duplex half, and on the port-channel interface, set allowed VLANs to 10,20,30.
Why wrong: This is incorrect because it sets speed to 100 and duplex half, which does not match SW1's speed 1000 and duplex full. The mismatch prevents the EtherChannel from forming.
- C
On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 10,20.
Why wrong: This is incorrect because the allowed VLAN list on the port-channel interface is missing VLAN 30, which is required by the trunk configuration. The EtherChannel may form but will not pass traffic for VLAN 30.
- D
On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 1-4094.
Why wrong: This is incorrect because allowing all VLANs (1-4094) is not the same as explicitly allowing only VLANs 10, 20, and 30. The requirement specifies a restricted set, and using 'allowed vlan all' may introduce security or operational issues.
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.
You are connected to SW1. Configure an LACP EtherChannel between SW1 and SW2 using interfaces GigabitEthernet0/1 and GigabitEthernet0/2. The port-channel interface must be configured as a trunk allowing VLANs 10, 20, and 30. Currently, the channel is not forming due to a mismatch in speed/duplex and VLAN configuration on SW2. Troubleshoot and resolve the issue so that the EtherChannel comes up as a Layer 2 trunk.
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
On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 10,20,30.
The EtherChannel is not forming because SW2's interfaces have speed 100 and duplex half, while SW1's interfaces have speed 1000 and duplex full. Additionally, the allowed VLANs on SW2's trunk must include VLAN 30, and this should be configured on the port-channel interface, not the physical interfaces. To fix, on SW2, set the speed to 1000 and duplex to full on Gi0/1 and Gi0/2, then on the port-channel interface, configure allowed VLANs 10,20,30. After these changes, the channel will come up as a Layer 2 trunk.
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.
- ✓
On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 10,20,30.
- ✗
On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 100, duplex half, and on the port-channel interface, set allowed VLANs to 10,20,30.
Why it's wrong here
This is incorrect because it sets speed to 100 and duplex half, which does not match SW1's speed 1000 and duplex full. The mismatch prevents the EtherChannel from forming.
- ✗
On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 10,20.
Why it's wrong here
This is incorrect because the allowed VLAN list on the port-channel interface is missing VLAN 30, which is required by the trunk configuration. The EtherChannel may form but will not pass traffic for VLAN 30.
- ✗
On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 1-4094.
Why it's wrong here
This is incorrect because allowing all VLANs (1-4094) is not the same as explicitly allowing only VLANs 10, 20, and 30. The requirement specifies a restricted set, and using 'allowed vlan all' may introduce security or operational issues.
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.
✓On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 10,20,30.Correct answer▾
Why this is correct
This resolves the speed/duplex mismatch by matching SW1's settings and adds VLAN 30 to the allowed list, meeting the trunk requirements. LACP requires consistent speed and duplex across all member links.
✗On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 100, duplex half, and on the port-channel interface, set allowed VLANs to 10,20,30.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that LACP requires all member interfaces to have identical speed and duplex settings; changing SW2 to 100/half does not match SW1's 1000/full.
Why candidates choose this
Candidates might think they need to make both sides consistent by lowering SW1's settings, but the correct approach is to match the higher-capability side.
✗On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 10,20.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the trunk must allow all required VLANs; omitting VLAN 30 violates the requirement.
Why candidates choose this
Candidates might focus only on the speed/duplex issue and forget to update the VLAN allowed list, especially if they assume the existing list is correct.
✗On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 1-4094.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the configuration does not match the requirement to allow only VLANs 10, 20, and 30; it allows all VLANs instead.
Why candidates choose this
Candidates might think 'allowed vlan all' is a quick fix that covers the required VLANs, but it is overly permissive and not what the question asks for.
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.
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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: On SW2, configure interfaces GigabitEthernet0/1 and 0/2 with speed 1000, duplex full, and on the port-channel interface, set allowed VLANs to 10,20,30. — The EtherChannel is not forming because SW2's interfaces have speed 100 and duplex half, while SW1's interfaces have speed 1000 and duplex full. Additionally, the allowed VLANs on SW2's trunk must include VLAN 30, and this should be configured on the port-channel interface, not the physical interfaces. To fix, on SW2, set the speed to 1000 and duplex to full on Gi0/1 and Gi0/2, then on the port-channel interface, configure allowed VLANs 10,20,30. After these changes, the channel will come up as a Layer 2 trunk.
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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