This 350-401 practice question tests your understanding of netflow and telemetry. 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:
SW1# show spanning-tree vlan 10
VLAN0010
Spanning tree enabled protocol ieee
Root ID Priority 32778
Address 0011.2233.4455
Cost 19
Port 1 (GigabitEthernet0/1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)
Address 0011.2233.4466
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Why wrong: The root bridge has address 0011.2233.4455, while the local switch's bridge ID has address 0011.2233.4466, so it is not the root.
B
The local switch is not the root bridge for VLAN 10
The root ID shows a different MAC address than the bridge ID of the local switch, indicating the local switch is not the root.
C
Interface Gi0/2 is in a forwarding state
Why wrong: The output shows Gi0/2 is in BLK (blocking) state, not forwarding.
D
The spanning-tree mode is Rapid PVST+
Why wrong: The output shows 'protocol ieee', which indicates standard 802.1D STP, not Rapid PVST+ (which would show 'protocol ieee' with different port roles).
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The local switch is not the root bridge for VLAN 10
The output shows spanning-tree information for VLAN 10. The root bridge has priority 32778 and address 0011.2233.4455. The local switch has a different bridge ID (0011.2233.4466), so it is not the root. Interface Gi0/1 is the root port (Root, FWD), and Gi0/2 is an alternate port (Altn, BLK). The correct answer is that the local switch is not the root bridge for VLAN 10.
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 local switch is the root bridge for VLAN 10
Why it's wrong here
The root bridge has address 0011.2233.4455, while the local switch's bridge ID has address 0011.2233.4466, so it is not the root.
✓
The local switch is not the root bridge for VLAN 10
Why this is correct
The root ID shows a different MAC address than the bridge ID of the local switch, indicating the local switch is not the root.
Related concept
Access ports place end devices into a single VLAN.
✗
Interface Gi0/2 is in a forwarding state
Why it's wrong here
The output shows Gi0/2 is in BLK (blocking) state, not forwarding.
✗
The spanning-tree mode is Rapid PVST+
Why it's wrong here
The output shows 'protocol ieee', which indicates standard 802.1D STP, not Rapid PVST+ (which would show 'protocol ieee' with different port roles).
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 output shows Gi0/2 is in BLK (blocking) state, not forwarding.
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 350-401 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 350-401 questions on switching, trunking, and access-port configuration.
NetFlow and Telemetry — This question tests NetFlow and Telemetry — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: The local switch is not the root bridge for VLAN 10 — The output shows spanning-tree information for VLAN 10. The root bridge has priority 32778 and address 0011.2233.4455. The local switch has a different bridge ID (0011.2233.4466), so it is not the root. Interface Gi0/1 is the root port (Root, FWD), and Gi0/2 is an alternate port (Altn, BLK). The correct answer is that the local switch is not the root bridge for VLAN 10.
What should I do if I get this 350-401 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 350-401 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.
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