The answer is that the interface is configured as a trunk port, which is why it does not appear in the output of show vlan brief. This command specifically displays only access ports and their assigned VLANs, whether statically or dynamically learned via VTP; trunk ports are omitted because they carry traffic for multiple VLANs simultaneously and are not tied to a single VLAN in that table. On the CCNA 200-301 v2 exam, this question tests your understanding of the fundamental difference between access and trunk port behavior in switch configurations, often appearing as a common trap where candidates assume a missing port indicates a misconfigured VLAN or a shutdown interface. A key memory tip is to remember that show vlan brief shows "access only"—if a port is missing, think "trunk or shutdown," but since VLAN 10 is active with other ports, trunk is the likely culprit.
CCNA Switching and Network Access Practice Question
This 200-301 practice question tests your understanding of switching and network access. 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.
Exhibit
SW2# show vlan brief
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Gi0/1, Gi0/3, Gi0/4, Gi0/5
Gi0/6, Gi0/7, Gi0/8
10 Sales active Gi0/9, Gi0/10, Gi0/11
20 Engineering active Gi0/12, Gi0/13
30 Management active Gi0/14
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
Refer to the exhibit. A network administrator runs the show vlan brief command on SW2. Interface GigabitEthernet0/2 is intended to be an access port in VLAN 10, but it does not appear in the output. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
SW2# show vlan brief
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Gi0/1, Gi0/3, Gi0/4, Gi0/5
Gi0/6, Gi0/7, Gi0/8
10 Sales active Gi0/9, Gi0/10, Gi0/11
20 Engineering active Gi0/12, Gi0/13
30 Management active Gi0/14
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
A
The interface is configured with switchport mode dynamic auto and no trunk has been negotiated, causing it to be hidden.
Why wrong: A port in dynamic auto mode begins as an access port and will appear in show vlan brief under the default VLAN until negotiation turns it into a trunk. It is not hidden from the output.
B
The interface is administratively shut down, and down ports are excluded from the show vlan brief output.
Why wrong: An access port that is shut down still appears in the Ports column of show vlan brief as a member of its assigned VLAN. Administrative state does not affect its listing.
C
The interface is configured as a trunk port and therefore does not appear under any VLAN in show vlan brief.
show vlan brief only displays ports that are in access mode. Trunk ports are not included because they belong to all VLANs allowed on the trunk. The output shows VLAN 10 with members Gi0/9–Gi0/11 but not Gi0/2, confirming it is not an access port.
D
VLAN 10 is not active, so the port assigned to it is not displayed in the listing.
Why wrong: The exhibit clearly shows VLAN 10 as active ('active') with multiple member ports (Gi0/9, Gi0/10, Gi0/11). The VLAN state is valid, eliminating this possibility.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The interface is configured as a trunk port and therefore does not appear under any VLAN in show vlan brief.
The show vlan brief command lists only access ports that are statically or dynamically assigned to a VLAN. Trunk ports carry traffic for multiple VLANs and are not displayed in this table. The absence of GigabitEthernet0/2, despite VLAN 10 being active and containing other ports, indicates that the interface is likely operating as a trunk port.
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 interface is configured with switchport mode dynamic auto and no trunk has been negotiated, causing it to be hidden.
Why it's wrong here
A port in dynamic auto mode begins as an access port and will appear in show vlan brief under the default VLAN until negotiation turns it into a trunk. It is not hidden from the output.
✗
The interface is administratively shut down, and down ports are excluded from the show vlan brief output.
Why it's wrong here
An access port that is shut down still appears in the Ports column of show vlan brief as a member of its assigned VLAN. Administrative state does not affect its listing.
✓
The interface is configured as a trunk port and therefore does not appear under any VLAN in show vlan brief.
Why this is correct
show vlan brief only displays ports that are in access mode. Trunk ports are not included because they belong to all VLANs allowed on the trunk. The output shows VLAN 10 with members Gi0/9–Gi0/11 but not Gi0/2, confirming it is not an access port.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
✗
VLAN 10 is not active, so the port assigned to it is not displayed in the listing.
Why it's wrong here
The exhibit clearly shows VLAN 10 as active ('active') with multiple member ports (Gi0/9, Gi0/10, Gi0/11). The VLAN state is valid, eliminating this possibility.
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 interface is configured as a trunk port and therefore does not appear under any VLAN in show vlan brief.Correct answer▾
Why this is correct
show vlan brief only displays ports that are in access mode. Trunk ports are not included because they belong to all VLANs allowed on the trunk. The output shows VLAN 10 with members Gi0/9–Gi0/11 but not Gi0/2, confirming it is not an access port.
✗The interface is configured with switchport mode dynamic auto and no trunk has been negotiated, causing it to be hidden.Wrong answer — click to see why▾
Why this is wrong here
Confusion about how dynamic trunking protocol (DTP) modes interact with VLAN membership display.
✗The interface is administratively shut down, and down ports are excluded from the show vlan brief output.Wrong answer — click to see why▾
Why this is wrong here
Misconception that only operational interfaces are shown in VLAN membership tables.
✗VLAN 10 is not active, so the port assigned to it is not displayed in the listing.Wrong answer — click to see why▾
Why this is wrong here
Overlooking the explicit 'active' status and port list for VLAN 10 in the output.
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
A port in dynamic auto mode begins as an access port and will appear in show vlan brief under the default VLAN until negotiation turns it into a trunk. It is not hidden from the output.
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 interface is configured as a trunk port and therefore does not appear under any VLAN in show vlan brief. — The show vlan brief command lists only access ports that are statically or dynamically assigned to a VLAN. Trunk ports carry traffic for multiple VLANs and are not displayed in this table. The absence of GigabitEthernet0/2, despite VLAN 10 being active and containing other ports, indicates that the interface is likely operating as a trunk port.
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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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