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Question 209 of 1,052
hardmultiple choiceObjective-mapped
CCNA Practice Question: Configures an EtherChannel between two Cisco…
This 200-301 practice question tests your understanding of 200-301 exam topics. 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.
Exhibit
SW1# show etherchannel summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use N - not in use, no aggregation
f - failed to allocate aggregator
M - not in use, no aggregation due to minimum links not met
m - not in use, port not aggregated due to minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(RU) LACP Gi0/0(P) Gi0/1(P) Gi0/2(P) Gi0/3(P)A network engineer configures an EtherChannel between two Cisco switches SW1 and SW2 using LACP. After configuration, hosts connected to SW1 report intermittent connectivity to hosts on SW2. The engineer checks the EtherChannel status and sees the following output. Which command should the engineer apply to both switches to resolve the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"which command"Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
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
✓
switchport trunk allowed vlan 1,10,20
The show etherchannel summary output shows all four ports in the (P) state, indicating they are bundled. However, the intermittent connectivity suggests a configuration mismatch. The most likely cause is that the allowed VLANs on the trunk ports are not identical across all member ports. When using LACP, all ports in the channel must have the same VLAN configuration. The command 'switchport trunk allowed vlan 1,10,20' ensures that all member ports permit the same set of VLANs, preventing traffic drops. Option A is wrong because the ports are already in mode 'active'. Option C is wrong because LACP rate fast is not required for stability. Option D is wrong because 'switchport mode trunk' is already configured and not the issue.
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.
- ✗
channel-group 1 mode active
Why it's wrong here
The ports are already in LACP active mode (as shown by the protocol being LACP and the ports being bundled). Reapplying this command will not fix the intermittent connectivity.
- ✓
switchport trunk allowed vlan 1,10,20
Why this is correct
This command ensures that all member ports of the EtherChannel have the same VLAN list. Inconsistent allowed VLANs across member ports can cause traffic to be dropped intermittently. Applying this to all member interfaces on both switches resolves the issue.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
- ✗
lacp rate fast
Why it's wrong here
This command changes the LACP rate to fast, which sends LACP packets every second instead of every 30 seconds. This would not cause intermittent connectivity; it is used for faster failure detection.
- ✗
switchport mode trunk
Why it's wrong here
The ports are already configured as trunk ports (the Po1 is Layer2 and trunking is implied). Reapplying this command will not resolve the intermittent connectivity.
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.
✓switchport trunk allowed vlan 1,10,20Correct answer▾
Why this is correct
This command ensures that all member ports of the EtherChannel have the same VLAN list. Inconsistent allowed VLANs across member ports can cause traffic to be dropped intermittently. Applying this to all member interfaces on both switches resolves the issue.
✗channel-group 1 mode activeWrong answer — click to see why▾
Why this is wrong here
The ports are already bundled, so the LACP mode is correct.
✗lacp rate fastWrong answer — click to see why▾
Why this is wrong here
The symptom is not related to LACP rate; it is a configuration mismatch issue.
✗switchport mode trunkWrong answer — click to see why▾
Why this is wrong here
The issue is not the trunk mode but the VLAN list consistency.
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.
Trap categories for this question
Command / output trap
The ports are already in LACP active mode (as shown by the protocol being LACP and the ports being bundled). Reapplying this command will not fix the intermittent connectivity.
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?
Access ports place end devices into a single VLAN.
What is the correct answer to this question?
The correct answer is: switchport trunk allowed vlan 1,10,20 — The show etherchannel summary output shows all four ports in the (P) state, indicating they are bundled. However, the intermittent connectivity suggests a configuration mismatch. The most likely cause is that the allowed VLANs on the trunk ports are not identical across all member ports. When using LACP, all ports in the channel must have the same VLAN configuration. The command 'switchport trunk allowed vlan 1,10,20' ensures that all member ports permit the same set of VLANs, preventing traffic drops. Option A is wrong because the ports are already in mode 'active'. Option C is wrong because LACP rate fast is not required for stability. Option D is wrong because 'switchport mode trunk' is already configured and not the issue.
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.
Are there clue words in this question I should notice?
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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