CCNA Switching and Network Access Practice Question
This 200-301 practice question tests your understanding of switching and network access. 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.
Network Topology
You are connected to switch SW1. The network uses Rapid-PVST+ and SW1 has been accidentally configured with a low spanning-tree priority, causing it to become the root bridge for VLAN 10 even though it should not be. Additionally, an edge port connected to a server is repeatedly receiving BPDUs, causing it to go into err-disabled state. Configure SW1 so that it is never the root bridge for VLAN 10, and configure the edge port so that it automatically recovers from err-disabled state after 300 seconds. Finally, verify that SW1 is not the root bridge for VLAN 10.
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "never"
Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
SW1# show running-config | section interface
interface GigabitEthernet0/0
description Link to SW2
switchport mode trunk
spanning-tree vlan 10 priority 4096
!
interface GigabitEthernet0/1
description Server Port
switchport mode access
switchport access vlan 10
spanning-tree portfast
!
SW1# show spanning-tree vlan 10
VLAN0010
Spanning tree enabled protocol rstp
Root ID Priority 4096
Address aabb.cc00.0100
This bridge is the root
Bridge ID Priority 4096 (priority 4096 sys-id-ext 10)
Address aabb.cc00.0100
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- ------------------------------
Gi0/0 Desg FWD 4 128.1 P2p
Gi0/1 Desg FWD 4 128.2 P2p Edge
SW1# show interfaces status | include Gi0/1
Gi0/1 err-disabled auto auto 10/100/1000
A
spanning-tree vlan 10 priority 36864; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10
Setting the priority to 36864 (or any value higher than the current root's priority) ensures SW1 will not become root for VLAN 10. The errdisable recovery commands enable automatic recovery from BPDU guard errdisable state after 300 seconds. The show command verifies SW1 is not the root.
B
spanning-tree vlan 10 priority 4096; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10
Why wrong: This is incorrect because setting the priority to 4096 is the same low value that caused the problem; it would still make SW1 the root bridge for VLAN 10.
C
spanning-tree vlan 10 root secondary; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10
Why wrong: This is incorrect because the 'root secondary' command sets the priority to 28672, which is still low enough to become root if the primary fails, but the question requires that SW1 never be root. Also, 'root secondary' does not guarantee it will never be root.
D
spanning-tree vlan 10 priority 32768; errdisable recovery cause all; errdisable recovery interval 300; show spanning-tree vlan 10
Why wrong: This is incorrect because 'errdisable recovery cause all' enables recovery for all errdisable causes, which is not specific to BPDU guard and may be too broad. The question specifically requires recovery from BPDU guard errdisable.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
spanning-tree vlan 10 priority 36864; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10
The issue is that SW1 has the spanning-tree priority for VLAN 10 set to 4096, which makes it the root bridge. To prevent this, you must set the priority higher than the current root bridge's priority (e.g., 32768 or higher). Additionally, the edge port (G0/1) is in err-disabled state because it received a BPDU while PortFast was enabled (BPDU Guard triggered). To automatically recover from err-disabled, you need to configure errdisable recovery cause bpduguard and set the interval to 300 seconds. After configuration, verify with 'show spanning-tree vlan 10' that SW1 is no longer the root and 'show errdisable recovery' to confirm the recovery settings.
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.
✓
spanning-tree vlan 10 priority 36864; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10
Why this is correct
Setting the priority to 36864 (or any value higher than the current root's priority) ensures SW1 will not become root for VLAN 10. The errdisable recovery commands enable automatic recovery from BPDU guard errdisable state after 300 seconds. The show command verifies SW1 is not the root.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
✗
spanning-tree vlan 10 priority 4096; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10
Why it's wrong here
This is incorrect because setting the priority to 4096 is the same low value that caused the problem; it would still make SW1 the root bridge for VLAN 10.
✗
spanning-tree vlan 10 root secondary; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10
Why it's wrong here
This is incorrect because the 'root secondary' command sets the priority to 28672, which is still low enough to become root if the primary fails, but the question requires that SW1 never be root. Also, 'root secondary' does not guarantee it will never be root.
✗
spanning-tree vlan 10 priority 32768; errdisable recovery cause all; errdisable recovery interval 300; show spanning-tree vlan 10
Why it's wrong here
This is incorrect because 'errdisable recovery cause all' enables recovery for all errdisable causes, which is not specific to BPDU guard and may be too broad. The question specifically requires recovery from BPDU guard errdisable.
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.
✓spanning-tree vlan 10 priority 36864; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10Correct answer▾
Why this is correct
Setting the priority to 36864 (or any value higher than the current root's priority) ensures SW1 will not become root for VLAN 10. The errdisable recovery commands enable automatic recovery from BPDU guard errdisable state after 300 seconds. The show command verifies SW1 is not the root.
✗spanning-tree vlan 10 priority 4096; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10Wrong answer — click to see why▾
Why this is wrong here
The priority 4096 is too low and would still result in SW1 being the root bridge.
Why candidates choose this
Candidates might think that since 4096 is the default for some switches, it is acceptable, but the goal is to prevent SW1 from becoming root, so a higher priority is needed.
✗spanning-tree vlan 10 root secondary; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10Wrong answer — click to see why▾
Why this is wrong here
The 'root secondary' command does not prevent the switch from becoming root; it only makes it the backup root.
Why candidates choose this
Candidates may confuse 'root secondary' with a command that prevents root selection, but it actually sets a low priority for failover.
✗spanning-tree vlan 10 priority 32768; errdisable recovery cause all; errdisable recovery interval 300; show spanning-tree vlan 10Wrong answer — click to see why▾
Why this is wrong here
Using 'cause all' is not the best practice; the requirement is to recover from bpduguard specifically.
Why candidates choose this
Candidates might think 'cause all' is acceptable because it includes bpduguard, but it is not the precise configuration asked for.
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
This is incorrect because the 'root secondary' command sets the priority to 28672, which is still low enough to become root if the primary fails, but the question requires that SW1 never be root. Also, 'root secondary' does not guarantee it will never be root.
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: spanning-tree vlan 10 priority 36864; errdisable recovery cause bpduguard; errdisable recovery interval 300; show spanning-tree vlan 10 — The issue is that SW1 has the spanning-tree priority for VLAN 10 set to 4096, which makes it the root bridge. To prevent this, you must set the priority higher than the current root bridge's priority (e.g., 32768 or higher). Additionally, the edge port (G0/1) is in err-disabled state because it received a BPDU while PortFast was enabled (BPDU Guard triggered). To automatically recover from err-disabled, you need to configure errdisable recovery cause bpduguard and set the interval to 300 seconds. After configuration, verify with 'show spanning-tree vlan 10' that SW1 is no longer the root and 'show errdisable recovery' to confirm the recovery settings.
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: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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