The answer is that the EtherChannel will not form because the physical interfaces have mismatched speed, duplex, and VLAN assignments, which are non-negotiable prerequisites for any LACP or PAgP bundle. For an EtherChannel to operate correctly, all member interfaces must share identical speed (e.g., 1000), duplex (full), and VLAN membership; here, Gi0/1 runs at 100/half on VLAN 10 while Gi0/2 runs at 1000/full on VLAN 20, creating an immediate incompatibility that prevents the port-channel from coming up. On the CCNA 200-301 v2 exam, this scenario tests your understanding that LACP mode active on both sides is necessary but insufficient—you must first resolve these Layer 1 and Layer 2 mismatches by unifying speed to 1000, duplex to full, and access VLAN to 10 on both interfaces before applying channel-group 1 mode active. A common trap is assuming LACP will auto-negotiate differences, but it strictly enforces consistency; a quick memory tip is “Same Speed, Same Duplex, Same VLAN—or no channel can stand.”
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
You are connected to SW1. The current configurations of interfaces GigabitEthernet0/1 and GigabitEthernet0/2 are as follows:
The port-channel interface 1 does not exist. Configure a LACP EtherChannel between SW1 and SW2 using these two interfaces, with port-channel 1 and mode active on both sides. Ensure the channel forms by resolving any speed/duplex or VLAN mismatches. After configuration, verify with 'show etherchannel summary'.
The EtherChannel will not form because the physical interfaces have mismatched speed/duplex and VLAN assignments. You must configure both interfaces with the same speed (1000), duplex (full), and access VLAN (10), then apply channel-group 1 mode active on each.
This is correct because LACP requires all member interfaces to have identical speed, duplex, and VLAN configuration. Mismatches cause the channel to fail. The fix is to unify these parameters and then set channel-group mode active on both interfaces.
B
The EtherChannel will form successfully because LACP active mode negotiates the channel regardless of speed/duplex or VLAN differences.
Why wrong: This is incorrect because LACP does not override speed/duplex or VLAN mismatches; these must match on all member interfaces for the channel to form.
C
The EtherChannel will not form because the port-channel interface must be configured with the same VLAN as the physical interfaces, but the physical interfaces can have different speeds.
Why wrong: This is incorrect because speed must match on all physical interfaces; different speeds prevent the channel from forming.
D
The EtherChannel will form successfully because the port-channel interface inherits the VLAN from the first physical interface added, so no additional configuration is needed.
Why wrong: This is incorrect because the port-channel interface does not automatically inherit VLAN settings; it must be explicitly configured, and all physical interfaces must have matching VLANs.
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 not form because the physical interfaces have mismatched speed/duplex and VLAN assignments. You must configure both interfaces with the same speed (1000), duplex (full), and access VLAN (10), then apply channel-group 1 mode active on each.
The EtherChannel fails because member interfaces have mismatched speed/duplex (Gi0/1 is 100/half, Gi0/2 is 1000/full) and different VLANs (VLAN 10 vs 20). Additionally, the port-channel interface and physical interfaces must have matching VLAN assignments. To fix, unify both physical interfaces to the same speed (1000), duplex (full), and access VLAN (10). Then set channel-group mode active on each physical interface. Finally, ensure the port-channel interface also uses VLAN 10. Verify with 'show etherchannel summary' which should show the port-channel as SU (in use).
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 not form because the physical interfaces have mismatched speed/duplex and VLAN assignments. You must configure both interfaces with the same speed (1000), duplex (full), and access VLAN (10), then apply channel-group 1 mode active on each.
Why this is correct
This is correct because LACP requires all member interfaces to have identical speed, duplex, and VLAN configuration. Mismatches cause the channel to fail. The fix is to unify these parameters and then set channel-group mode active on both interfaces.
Related concept
Access ports place end devices into a single VLAN.
✗
The EtherChannel will form successfully because LACP active mode negotiates the channel regardless of speed/duplex or VLAN differences.
Why it's wrong here
This is incorrect because LACP does not override speed/duplex or VLAN mismatches; these must match on all member interfaces for the channel to form.
✗
The EtherChannel will not form because the port-channel interface must be configured with the same VLAN as the physical interfaces, but the physical interfaces can have different speeds.
Why it's wrong here
This is incorrect because speed must match on all physical interfaces; different speeds prevent the channel from forming.
✗
The EtherChannel will form successfully because the port-channel interface inherits the VLAN from the first physical interface added, so no additional configuration is needed.
Why it's wrong here
This is incorrect because the port-channel interface does not automatically inherit VLAN settings; it must be explicitly configured, and all physical interfaces must have matching VLANs.
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.
✓The EtherChannel will not form because the physical interfaces have mismatched speed/duplex and VLAN assignments. You must configure both interfaces with the same speed (1000), duplex (full), and access VLAN (10), then apply channel-group 1 mode active on each.Correct answer▾
Why this is correct
This is correct because LACP requires all member interfaces to have identical speed, duplex, and VLAN configuration. Mismatches cause the channel to fail. The fix is to unify these parameters and then set channel-group mode active on both interfaces.
✗The EtherChannel will form successfully because LACP active mode negotiates the channel regardless of speed/duplex or VLAN differences.Wrong answer — click to see why▾
Why this is wrong here
LACP active mode only enables negotiation, but it does not resolve underlying parameter mismatches. The interfaces must still have consistent speed, duplex, and VLAN configuration.
Why candidates choose this
Candidates may think that LACP's negotiation capability can automatically adjust or ignore mismatches, but it only handles aggregation, not physical or VLAN parameters.
✗The EtherChannel will not form because the port-channel interface must be configured with the same VLAN as the physical interfaces, but the physical interfaces can have different speeds.Wrong answer — click to see why▾
Why this is wrong here
All member interfaces must have identical speed and duplex settings. Even if VLANs match, speed mismatch will cause the channel to fail.
Why candidates choose this
Candidates might know that VLAN consistency is required but underestimate the importance of speed/duplex matching, thinking LACP can handle speed differences.
✗The EtherChannel will form successfully because the port-channel interface inherits the VLAN from the first physical interface added, so no additional configuration is needed.Wrong answer — click to see why▾
Why this is wrong here
The port-channel interface is a logical interface that requires its own VLAN configuration. Physical interfaces must have identical VLAN assignments; otherwise, the channel will not form.
Why candidates choose this
Candidates may think that adding physical interfaces to a port-channel automatically synchronizes VLAN settings, but in reality, mismatches cause the channel to fail.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 200-301 question in full detail.
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.
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: The EtherChannel will not form because the physical interfaces have mismatched speed/duplex and VLAN assignments. You must configure both interfaces with the same speed (1000), duplex (full), and access VLAN (10), then apply channel-group 1 mode active on each. — The EtherChannel fails because member interfaces have mismatched speed/duplex (Gi0/1 is 100/half, Gi0/2 is 1000/full) and different VLANs (VLAN 10 vs 20). Additionally, the port-channel interface and physical interfaces must have matching VLAN assignments. To fix, unify both physical interfaces to the same speed (1000), duplex (full), and access VLAN (10). Then set channel-group mode active on each physical interface. Finally, ensure the port-channel interface also uses VLAN 10. Verify with 'show etherchannel summary' which should show the port-channel as SU (in use).
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.
About these practice questions
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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. 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.
hard
✓ 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.
Why A: 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).
Variation 2. Drag and drop the following steps into the correct order to configure an LACP EtherChannel on two Cisco switches using active mode.
medium
✓ A.Enter interface configuration mode for the physical ports (interface range gigabitethernet 0/1-2).
✓ B.Configure the channel-group for the interfaces using mode active (channel-group 1 mode active).
✓ C.Optionally configure the Port-Channel interface (for example, switchport mode trunk).
✓ D.Verify the EtherChannel status with the show etherchannel summary command.
Why A: To configure an LACP EtherChannel in active mode, you must first enter interface configuration mode on the physical interfaces (e.g., using interface range). Next, assign those interfaces to a channel group using the channel-group command with the mode active keyword; this enables LACP negotiation and ensures the switch actively attempts to form a bundle. After the member ports are configured, you can optionally set parameters on the Port-Channel interface (such as switchport mode trunk). Finally, verify the EtherChannel is operational with show etherchannel summary. Using mode passive, on, or desirable would not enable LACP active negotiation or would use a different protocol (PAgP), which does not meet the requirement.
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