CCNA Switching and Network Access Practice Question
Network Topology
You are connected to SW1. A LACP EtherChannel between SW1 and SW2 has already been configured using interfaces GigabitEthernet0/1 and GigabitEthernet0/2 with channel-group 1 mode active on both sides and assigned to VLAN 100. However, the channel is not forming because of a speed/duplex mismatch. The correct interface settings for this network are speed 1000 and duplex full. Interface GigabitEthernet0/1 is already configured with these settings. Only interface GigabitEthernet0/2 needs to be corrected. Identify the configuration change needed to resolve the mismatch and verify the EtherChannel is up with 'show etherchannel summary'.
⚠ Common exam trap
The trap is that candidates may overlook the speed/duplex mismatch and focus only on the LACP mode or VLAN configuration. Always verify that all physical parameters match before troubleshooting EtherChannel formation.
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 interface GigabitEthernet0/2 with 'speed 1000' and 'duplex full', then verify the EtherChannel is up.
The EtherChannel is not forming because GigabitEthernet0/2 is configured with speed 100 and duplex half, while GigabitEthernet0/1 is speed 1000 and duplex full. LACP requires all member ports to have identical speed and duplex settings. To fix this, configure GigabitEthernet0/2 with speed 1000 and duplex full, matching GigabitEthernet0/1. After correction, the ports should bundle in Port-channel1 and show as bundled (P) in 'show etherchannel summary'.
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 interface GigabitEthernet0/2 with 'speed 1000' and 'duplex full', then verify the EtherChannel is up.
Why this is correct
LACP requires every member port in an EtherChannel to have identical operational settings, and GigabitEthernet0/1 is already configured with speed 1000 and duplex full. By setting GigabitEthernet0/2 to the same speed and duplex, you remove the mismatch that is preventing LACP from forming the bundle. After applying these commands, use 'show etherchannel summary' to confirm the port-channel has transitioned to a bundled/up state.
- ✗
Configure interface GigabitEthernet0/1 with 'speed 100' and 'duplex half', then verify the EtherChannel is up.
Why it's wrong here
This is incorrect because it would make both ports use speed 100 and duplex half, but GigabitEthernet0/1 is a GigabitEthernet interface that typically supports 1000 Mbps full duplex. Forcing it to 100/half would degrade performance and may not be supported, and it does not match the intended configuration.
- ✗
Configure interface GigabitEthernet0/2 with 'speed auto' and 'duplex auto', then verify the EtherChannel is up.
Why it's wrong here
This is incorrect because setting speed and duplex to auto on GigabitEthernet0/2 may result in auto-negotiation settling on a different speed/duplex than the manually configured GigabitEthernet0/1 (speed 1000, duplex full). LACP requires all ports to have identical operational speed and duplex, so auto could cause a mismatch.
- ✗
Configure interface GigabitEthernet0/2 with 'channel-group 1 mode active' and 'switchport access vlan 100', then verify the EtherChannel is up.
Why it's wrong here
Issuing 'channel-group 1 mode active' does enable LACP on GigabitEthernet0/2, but it does nothing to correct the speed/duplex mismatch with GigabitEthernet0/1. Because LACP compares physical parameters during negotiation, the port will fail to aggregate and remain suspended even though the channel-group is configured. Adding 'switchport access vlan 100' is also unrelated to the problem and may actually introduce a VLAN inconsistency if the peer port is in a different access VLAN.
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 interface GigabitEthernet0/2 with 'speed 1000' and 'duplex full', then verify the EtherChannel is up.Correct answer▾
Why this is correct
LACP requires every member port in an EtherChannel to have identical operational settings, and GigabitEthernet0/1 is already configured with speed 1000 and duplex full. By setting GigabitEthernet0/2 to the same speed and duplex, you remove the mismatch that is preventing LACP from forming the bundle. After applying these commands, use 'show etherchannel summary' to confirm the port-channel has transitioned to a bundled/up state.
✗Configure interface GigabitEthernet0/1 with 'speed 100' and 'duplex half', then verify the EtherChannel is up.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the question implies the correct configuration should use speed 1000 and duplex full, not downgrade to 100/half. Also, LACP requires identical settings, but the goal is to match the higher speed.
Why candidates choose this
Candidates might think that making both ports match is sufficient, regardless of the speed/duplex values, but they overlook that the intended configuration is speed 1000/full.
✗Configure interface GigabitEthernet0/2 with 'speed auto' and 'duplex auto', then verify the EtherChannel is up.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that auto-negotiation does not guarantee matching settings when one side is manually configured. The mismatch would persist.
Why candidates choose this
Candidates might think 'auto' is a safe default that will negotiate correctly, but they forget that the other port is statically configured, leading to potential mismatch.
✗Configure interface GigabitEthernet0/2 with 'channel-group 1 mode active' and 'switchport access vlan 100', then verify the EtherChannel is up.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that the question explicitly states a speed/duplex mismatch prevents the channel from forming, and this option does not correct that mismatch.
Why candidates choose this
Candidates might focus on the LACP configuration and VLAN assignment, forgetting that speed/duplex consistency is a prerequisite for EtherChannel formation.
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?”
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Related to this question
Learn chapter
Configuring Switch Ports for Desktops, VoIP Phones, APs, IoT, and Virtualized Hosts
Key term
Link Aggregation Control Protocol
Link Aggregation Control Protocol (LACP) is a standard protocol that automatically bundles multiple physical network links into a single logical link to increase bandwidth and provide redundancy.
Key term
VLAN
A VLAN logically segments a physical network into isolated broadcast domains without requiring separate physical switches.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.