The answer is to configure the spanning-tree vlan 10 priority 4096 command on MLSW1, then recover the err-disabled port by issuing shutdown followed by no shutdown on interface GigabitEthernet0/1, and finally verify the blocking port on MLSW2 using show spanning-tree vlan 10. This is correct because setting the priority to 4096 ensures MLSW1 becomes the root bridge for VLAN 10, and since BPDU Guard triggered the err-disabled state on a PortFast-enabled access port, the only way to recover is to manually cycle the interface. On the CCNA 200-301 v2 exam, this tests your ability to combine Rapid PVST+ root bridge configuration with BPDU Guard recovery—a common trap is forgetting that the root bridge has no blocking ports, so verification must be done on a downstream switch like MLSW2. A helpful memory tip: “Root has no blocking, so check the neighbor’s spanning-tree for the alternate.”
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 a multilayer switch MLSW1. PortFast and BPDU Guard have already been enabled on interface GigabitEthernet0/1, which connects to an end device, and a BPDU received on that interface placed it in the err-disabled state. Configure Rapid PVST+ so that MLSW1 becomes the root bridge for VLAN 10 with a priority of 4096. Recover the interface by re-enabling it. Finally, verify which port is blocking on VLAN 10 by connecting to MLSW2 and executing the appropriate show command.
MLSW1# show spanning-tree vlan 10
VLAN0010
Spanning tree enabled protocol rstp
Root ID Priority 32768
Address 0c75.15b6.0001
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768 (priority 32768 sys-id-ext 10)
Address 0c75.15b6.0001
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/1 Desg FWD 4 128.1 P2p
Gi0/2 Desg FWD 4 128.2 P2p
MLSW1# show interfaces gigabitEthernet 0/1 status
Port Name Status Vlan Duplex Speed Type
Gi0/1 err-disabled 10 full 1000 10/100/1000BaseTX
MLSW1# show running-config | section interface GigabitEthernet0/1
interface GigabitEthernet0/1
switchport mode access
switchport access vlan 10
spanning-tree portfast
spanning-tree bpduguard enable
A
spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show spanning-tree vlan 10
This sequence correctly sets the priority to 4096 for VLAN 10, recovers the err-disabled interface by toggling shutdown, and verifies the blocking port on another switch using 'show spanning-tree vlan 10'.
B
spanning-tree vlan 10 root primary; interface GigabitEthernet0/1; no shutdown; show spanning-tree vlan 10
Why wrong: This is incorrect because 'spanning-tree vlan 10 root primary' sets the priority to 24576, not 4096. Also, 'no shutdown' alone does not recover an err-disabled interface; a 'shutdown' must precede it.
C
spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; no shutdown; show interfaces status
Why wrong: This is incorrect because 'no shutdown' alone does not recover an err-disabled interface; a 'shutdown' must be issued first. Also, 'show interfaces status' does not show STP blocking ports; 'show spanning-tree vlan 10' is needed.
D
spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show running-config
Why wrong: This is incorrect because 'show running-config' does not show STP blocking ports; it shows the configuration. The correct verification command is 'show spanning-tree vlan 10'.
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 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show spanning-tree vlan 10
The correct solution sets the spanning-tree priority for VLAN 10 to 4096 on MLSW1, ensuring it becomes the root bridge. PortFast and BPDU Guard are already configured on G0/1, which caused the interface to go err-disabled when a BPDU was received. To recover, you must issue the 'shutdown' followed by 'no shutdown' commands on the interface. Because MLSW1 is the root bridge, it has no blocking ports; the blocking port (alternate) will be seen on a downstream switch like MLSW2. Therefore, verification must be done on MLSW2 using 'show spanning-tree vlan 10' to view the alternate blocking port. Option A correctly includes all required steps. Option B uses 'root primary' (priority 24576) instead of the specified 4096, lacks the recovery commands, and verifies on the wrong device. Option C omits the err-disabled recovery and uses the wrong verification command. Option D also verifies with 'show running-config', which does not display STP port roles.
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 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show spanning-tree vlan 10
Why this is correct
This sequence correctly sets the priority to 4096 for VLAN 10, recovers the err-disabled interface by toggling shutdown, and verifies the blocking port on another switch using 'show spanning-tree vlan 10'.
Related concept
Access ports place end devices into a single VLAN.
✗
spanning-tree vlan 10 root primary; interface GigabitEthernet0/1; no shutdown; show spanning-tree vlan 10
Why it's wrong here
This is incorrect because 'spanning-tree vlan 10 root primary' sets the priority to 24576, not 4096. Also, 'no shutdown' alone does not recover an err-disabled interface; a 'shutdown' must precede it.
✗
spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; no shutdown; show interfaces status
Why it's wrong here
This is incorrect because 'no shutdown' alone does not recover an err-disabled interface; a 'shutdown' must be issued first. Also, 'show interfaces status' does not show STP blocking ports; 'show spanning-tree vlan 10' is needed.
✗
spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show running-config
Why it's wrong here
This is incorrect because 'show running-config' does not show STP blocking ports; it shows the configuration. The correct verification command is 'show spanning-tree vlan 10'.
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 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show spanning-tree vlan 10Correct answer▾
Why this is correct
This sequence correctly sets the priority to 4096 for VLAN 10, recovers the err-disabled interface by toggling shutdown, and verifies the blocking port on another switch using 'show spanning-tree vlan 10'.
✗spanning-tree vlan 10 root primary; interface GigabitEthernet0/1; no shutdown; show spanning-tree vlan 10Wrong answer — click to see why▾
Why this is wrong here
The specific factual error: 'root primary' sets priority to 24576, not 4096. Also, err-disabled recovery requires a shutdown followed by no shutdown.
Why candidates choose this
Candidates pick this because 'root primary' is a common command to make a switch root, and they may think 'no shutdown' is sufficient to recover an interface.
✗spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; no shutdown; show interfaces statusWrong answer — click to see why▾
Why this is wrong here
The specific factual error: err-disabled recovery requires a shutdown before no shutdown. 'show interfaces status' does not display STP port roles.
Why candidates choose this
Candidates pick this because they know 'no shutdown' re-enables an interface, but forget that err-disabled requires a full shutdown cycle. They may also confuse 'show interfaces status' with 'show spanning-tree'.
✗spanning-tree vlan 10 priority 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show running-configWrong answer — click to see why▾
Why this is wrong here
The specific factual error: 'show running-config' does not display STP port roles or blocking status.
Why candidates choose this
Candidates pick this because they may think 'show running-config' verifies all configurations, but it does not show real-time STP state.
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 'no shutdown' alone does not recover an err-disabled interface; a 'shutdown' must be issued first. Also, 'show interfaces status' does not show STP blocking ports; 'show spanning-tree vlan 10' is needed.
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 4096; interface GigabitEthernet0/1; shutdown; no shutdown; show spanning-tree vlan 10 — The correct solution sets the spanning-tree priority for VLAN 10 to 4096 on MLSW1, ensuring it becomes the root bridge. PortFast and BPDU Guard are already configured on G0/1, which caused the interface to go err-disabled when a BPDU was received. To recover, you must issue the 'shutdown' followed by 'no shutdown' commands on the interface. Because MLSW1 is the root bridge, it has no blocking ports; the blocking port (alternate) will be seen on a downstream switch like MLSW2. Therefore, verification must be done on MLSW2 using 'show spanning-tree vlan 10' to view the alternate blocking port. Option A correctly includes all required steps. Option B uses 'root primary' (priority 24576) instead of the specified 4096, lacks the recovery commands, and verifies on the wrong device. Option C omits the err-disabled recovery and uses the wrong verification command. Option D also verifies with 'show running-config', which does not display STP port roles.
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.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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