- A
The EtherChannel will form using LACP, and the port-channel will operate as a trunk carrying VLANs 10, 20, and 30.
Correct. LACP active/passive will negotiate, and the port-channel trunk configuration applies to all member ports.
- B
The EtherChannel will not form because both sides must use the same LACP mode.
Why wrong: Incorrect. LACP active/passive is a valid combination; the active side initiates negotiation.
- C
The EtherChannel will form using PAgP because the mode is not specified as lacp.
Why wrong: Incorrect. The 'channel-group 1 mode active' command explicitly uses LACP, not PAgP.
- D
The EtherChannel will form but only VLAN 1 will be allowed on the trunk.
Why wrong: Incorrect. The 'switchport trunk allowed vlan' command restricts the trunk to VLANs 10, 20, and 30.
Quick Answer
The correct answer is that the EtherChannel will form using LACP, and the port-channel will operate as a trunk carrying VLANs 10, 20, and 30. This works because LACP active and passive mode negotiation allows a link to be established as long as at least one side is set to active; the active side initiates the LACP packets, while the passive side listens and responds, so the channel forms successfully. On the ENCOR 350-401 exam, this question tests your understanding of LACP negotiation states and how they interact with port-channel interface configurations—a common trap is assuming both sides must be active, but passive is perfectly fine as a responder. Remember that the port-channel interface inherits all Layer 2 settings, such as trunking and allowed VLANs, from the interface-level configuration. A helpful memory tip: “Active initiates, passive participates—one must talk for the link to walk.”
CCNP EtherChannel Practice Question
This 350-401 practice question tests your understanding of etherchannel. 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.
Consider the following configuration snippet:
interface Port-channel1 switchport mode trunk switchport trunk allowed vlan 10,20,30
!
interface GigabitEthernet0/1 channel-group 1 mode active
!
interface GigabitEthernet0/2 channel-group 1 mode passive
What is the effect of this configuration?
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
The EtherChannel will form using LACP, and the port-channel will operate as a trunk carrying VLANs 10, 20, and 30.
The configuration creates an EtherChannel using LACP with one side in active mode and the other in passive mode. The active side initiates negotiation, so the channel will form. The port-channel interface is configured as a trunk, so the channel will carry VLANs 10, 20, and 30.
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.
- ✓
The EtherChannel will form using LACP, and the port-channel will operate as a trunk carrying VLANs 10, 20, and 30.
Why this is correct
Correct. LACP active/passive will negotiate, and the port-channel trunk configuration applies to all member ports.
Related concept
Access ports place end devices into a single VLAN.
- ✗
The EtherChannel will not form because both sides must use the same LACP mode.
Why it's wrong here
Incorrect. LACP active/passive is a valid combination; the active side initiates negotiation.
- ✗
The EtherChannel will form using PAgP because the mode is not specified as lacp.
- ✗
The EtherChannel will form but only VLAN 1 will be allowed on the trunk.
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
Incorrect. The 'channel-group 1 mode active' command explicitly uses LACP, not PAgP.
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 350-401 questions on switching, trunking, and access-port configuration.
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FAQ
Questions learners often ask
What does this 350-401 question test?
EtherChannel — This question tests EtherChannel — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: The EtherChannel will form using LACP, and the port-channel will operate as a trunk carrying VLANs 10, 20, and 30. — The configuration creates an EtherChannel using LACP with one side in active mode and the other in passive mode. The active side initiates negotiation, so the channel will form. The port-channel interface is configured as a trunk, so the channel will carry VLANs 10, 20, and 30.
What should I do if I get this 350-401 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 350-401 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.
About these practice questions
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Same concept, more angles
1 more ways this is tested on 350-401
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Given the configuration: interface Port-channel1 switchport mode trunk switchport trunk allowed vlan 10-20 ! interface GigabitEthernet0/1 switchport mode trunk channel-group 1 mode passive ! interface GigabitEthernet0/2 switchport mode trunk channel-group 1 mode passive What is missing for this EtherChannel to form with a neighbor that uses LACP active?
medium- A.The member interfaces must also have the 'switchport trunk allowed vlan 10-20' command.
- B.The port-channel interface must be configured with 'channel-group 1' to associate the member ports.
- ✓ C.Nothing is missing; the configuration is valid and the EtherChannel will form with the neighbor.
- D.The member interfaces must use LACP active mode to form the channel.
Why C: The configuration uses LACP passive on both member interfaces. For LACP to negotiate, one side must be active. The neighbor is active, so that is fine. However, the port-channel interface does not have the 'switchport trunk allowed vlan' command applied; it is only on the port-channel. That is actually correct—the port-channel configuration applies to the channel. But the question asks what is missing; the answer is that the port-channel interface itself must have the allowed VLAN list, which it does. Actually, the configuration is complete. The trick is that the port-channel interface already has the allowed VLAN list. So nothing is missing. But the options might include a common mistake. Let's re-evaluate: The configuration shows the port-channel with allowed VLANs, and the member ports without. That is correct. So the answer is that nothing is missing. However, a common issue is that the member ports must also have the same allowed VLAN list if configured individually, but here they are not configured, so they inherit from the port-channel. This is fine. So the correct answer is that the configuration is valid.
Last reviewed: Jun 18, 2026
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