The answer is that interfaces Gi0/1, Gi0/2, and Gi0/3 are access ports assigned to VLAN 1. This is correct because the show vlan brief interpretation directly maps each listed port to its corresponding VLAN in the output, and VLAN 1 is the default VLAN on Cisco switches where all ports reside unless explicitly moved. On the ENCOR 350-401 exam, this command tests your ability to read VLAN-to-port assignments quickly, often as a foundation for troubleshooting Layer 2 connectivity or verifying segmentation. A common trap is assuming that ports not listed under a specific VLAN are inactive, but the default VLAN 1 always contains any unassigned access ports. Remember that the "Ports" column only shows active access ports in that VLAN, so if a port is missing from the output entirely, it is likely a trunk or in a different operational state. A useful memory tip: "VLAN 1 is home for the forgotten ones"—any port not explicitly configured for another VLAN will always show up under VLAN 1 in the brief output.
CCNP VLANs and Trunking Practice Question
This 350-401 practice question tests your understanding of vlans and trunking. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
A network engineer runs the following command on Switch SW1:
Why wrong: Trunk ports would appear in 'show interfaces trunk' or be listed with 'trunk' in 'show vlan brief' (some IOS versions show trunk ports as 'trunk' in the Ports column). Here, only access ports are listed.
B
VLANs 1002-1005 are active and supported.
Why wrong: They are shown as 'act/unsup' meaning active but unsupported on this hardware platform.
C
Interfaces Gi0/1, Gi0/2, and Gi0/3 are in VLAN 1.
The output clearly lists Gi0/1, Gi0/2, Gi0/3 under VLAN 1, indicating they are access ports in that VLAN.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Interfaces Gi0/1, Gi0/2, and Gi0/3 are in VLAN 1.
Option C is correct because the 'show vlan brief' output explicitly lists Gi0/1, Gi0/2, and Gi0/3 under VLAN 1 (default), confirming these interfaces are access ports assigned to VLAN 1. VLAN 1 is the default VLAN on Cisco switches, and all ports not explicitly configured otherwise belong to it.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
All ports shown are in trunk mode.
Why it's wrong here
Trunk ports would appear in 'show interfaces trunk' or be listed with 'trunk' in 'show vlan brief' (some IOS versions show trunk ports as 'trunk' in the Ports column). Here, only access ports are listed.
✗
VLANs 1002-1005 are active and supported.
Why it's wrong here
They are shown as 'act/unsup' meaning active but unsupported on this hardware platform.
✓
Interfaces Gi0/1, Gi0/2, and Gi0/3 are in VLAN 1.
Why this is correct
The output clearly lists Gi0/1, Gi0/2, Gi0/3 under VLAN 1, indicating they are access ports in that VLAN.
Related concept
Read the scenario before looking for a memorised answer.
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between access and trunk port representation in 'show vlan brief' versus 'show interfaces trunk', leading candidates to incorrectly assume all listed ports are trunk ports or that VLANs 1002-1005 are fully functional.
Trap categories for this question
Command / output trap
Trunk ports would appear in 'show interfaces trunk' or be listed with 'trunk' in 'show vlan brief' (some IOS versions show trunk ports as 'trunk' in the Ports column). Here, only access ports are listed.
Detailed technical explanation
How to think about this question
The 'show vlan brief' command displays the VLAN database and associated access ports; trunk ports are not listed here because they belong to multiple VLANs and are only shown in 'show interfaces trunk'. In real-world scenarios, misconfiguring a trunk port as an access port can cause VLAN mismatch issues, leading to connectivity loss or spanning-tree problems. Cisco switches automatically include all ports in VLAN 1 by default unless explicitly moved, which is a common source of security concerns if unused ports remain in the default VLAN.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
VLANs and Trunking — This question tests VLANs and Trunking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Interfaces Gi0/1, Gi0/2, and Gi0/3 are in VLAN 1. — Option C is correct because the 'show vlan brief' output explicitly lists Gi0/1, Gi0/2, and Gi0/3 under VLAN 1 (default), confirming these interfaces are access ports assigned to VLAN 1. VLAN 1 is the default VLAN on Cisco switches, and all ports not explicitly configured otherwise belong to it.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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