CCNA Switching and Network Access Practice Question
This 200-301 practice question tests your understanding of switching and network access. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 SW1. The network has three switches (SW1, SW2, SW3) running Rapid-PVST+. SW1 should be the root bridge for VLAN 10. PortFast and BPDU Guard must be enabled on all edge ports connected to end hosts. An err-disabled port (G0/1) has occurred due to a BPDU violation on an edge port. Recover the port and ensure it is configured correctly to prevent recurrence.
SW1#show spanning-tree vlan 10
VLAN0010
Spanning tree enabled protocol rstp
Root ID Priority 32778
Address aabb.cc00.0100
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)
Address aabb.cc00.0100
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/0 Desg FWD 4 128.1 P2p
Gi0/1 Desg BLK 4 128.2 P2p Edge
Gi0/2 Desg FWD 4 128.3 P2p
SW1#show interfaces gigabitEthernet 0/1 status
Port Name Status Vlan Duplex Speed Type
Gi0/1 err-disabled 10 auto auto 10/100/1000BaseTX
SW1#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
Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then configure 'spanning-tree bpduguard disable' on the interface.
Why wrong: This is incorrect because disabling BPDU Guard on the port would allow BPDUs to be received, which violates the requirement that BPDU Guard must be enabled on all edge ports. The port would remain vulnerable to BPDU attacks.
B
Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then configure 'spanning-tree portfast' and 'spanning-tree bpduguard enable' on the interface.
Why wrong: This is incorrect because the port already has PortFast and BPDU Guard enabled (as required). Re-enabling them does not address the root cause: the connected device is sending BPDUs. The port will go err-disabled again immediately after recovery.
C
Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then configure 'spanning-tree guard root' on the interface.
Why wrong: This is incorrect because Root Guard is used to prevent a port from becoming a root port, not to handle BPDU reception on edge ports. It does not prevent err-disabled state from BPDU Guard.
D
Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then verify that the connected device is not a switch or remove it from the network.
This is correct because the port is err-disabled due to BPDU Guard. After recovering with 'shutdown' and 'no shutdown', the root cause must be addressed: the connected device is sending BPDUs, which should not happen on an edge port. Either the device is not an end host (e.g., it is another switch) and should be connected to a trunk port, or it is a rogue device that should be removed. This ensures BPDU Guard remains enabled and the port stays up.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then verify that the connected device is not a switch or remove it from the network.
The port Gi0/1 is in err-disabled state because BPDU Guard disabled it after receiving a BPDU on a PortFast edge port. First, shut down the interface and then re-enable it with 'no shutdown' to recover from err-disabled. However, to prevent recurrence, the root cause must be addressed: the connected device (likely another switch) should not be sending BPDUs on an edge port. Optionally, you can disable BPDU Guard on that specific port if it is not truly an edge port, but the task requires PortFast and BPDU Guard on edge ports. The correct fix is to ensure no BPDUs are sent from the downstream device or use 'spanning-tree bpduguard disable' on that port if it is not an edge port (but the task mandates BPDU Guard). Since the scenario requires BPDU Guard, the candidate should recover the port and then verify that the connected device is not a switch (or remove it from the topology).
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then configure 'spanning-tree bpduguard disable' on the interface.
Why it's wrong here
This is incorrect because disabling BPDU Guard on the port would allow BPDUs to be received, which violates the requirement that BPDU Guard must be enabled on all edge ports. The port would remain vulnerable to BPDU attacks.
✗
Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then configure 'spanning-tree portfast' and 'spanning-tree bpduguard enable' on the interface.
Why it's wrong here
This is incorrect because the port already has PortFast and BPDU Guard enabled (as required). Re-enabling them does not address the root cause: the connected device is sending BPDUs. The port will go err-disabled again immediately after recovery.
✗
Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then configure 'spanning-tree guard root' on the interface.
Why it's wrong here
This is incorrect because Root Guard is used to prevent a port from becoming a root port, not to handle BPDU reception on edge ports. It does not prevent err-disabled state from BPDU Guard.
✓
Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then verify that the connected device is not a switch or remove it from the network.
Why this is correct
This is correct because the port is err-disabled due to BPDU Guard. After recovering with 'shutdown' and 'no shutdown', the root cause must be addressed: the connected device is sending BPDUs, which should not happen on an edge port. Either the device is not an end host (e.g., it is another switch) and should be connected to a trunk port, or it is a rogue device that should be removed. This ensures BPDU Guard remains enabled and the port stays up.
Related concept
Authentication checks who the user is.
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.
✓Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then verify that the connected device is not a switch or remove it from the network.Correct answer▾
Why this is correct
This is correct because the port is err-disabled due to BPDU Guard. After recovering with 'shutdown' and 'no shutdown', the root cause must be addressed: the connected device is sending BPDUs, which should not happen on an edge port. Either the device is not an end host (e.g., it is another switch) and should be connected to a trunk port, or it is a rogue device that should be removed. This ensures BPDU Guard remains enabled and the port stays up.
✗Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then configure 'spanning-tree bpduguard disable' on the interface.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that BPDU Guard should not be disabled on a port that is supposed to be an edge port with BPDU Guard enabled.
Why candidates choose this
Candidates may think that disabling BPDU Guard prevents the port from going err-disabled again, but this contradicts the requirement to keep BPDU Guard enabled.
✗Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then configure 'spanning-tree portfast' and 'spanning-tree bpduguard enable' on the interface.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that simply re-enabling the same features does not prevent recurrence; the source of BPDUs must be removed or the port must be reconfigured as a non-edge port.
Why candidates choose this
Candidates may think that re-applying the configuration ensures the port is correctly configured, but they overlook that the BPDU source is still present.
✗Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then configure 'spanning-tree guard root' on the interface.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that Root Guard and BPDU Guard serve different purposes; Root Guard does not stop BPDU Guard from disabling the port.
Why candidates choose this
Candidates may confuse Root Guard with BPDU Guard or think that any spanning-tree guard feature can solve the issue.
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: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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 Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 200-301 questions on access control and AAA configuration.
Switching and Network Access — This question tests Switching and Network Access — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: Enter interface configuration mode for Gi0/1, issue 'shutdown' followed by 'no shutdown', then verify that the connected device is not a switch or remove it from the network. — The port Gi0/1 is in err-disabled state because BPDU Guard disabled it after receiving a BPDU on a PortFast edge port. First, shut down the interface and then re-enable it with 'no shutdown' to recover from err-disabled. However, to prevent recurrence, the root cause must be addressed: the connected device (likely another switch) should not be sending BPDUs on an edge port. Optionally, you can disable BPDU Guard on that specific port if it is not truly an edge port, but the task requires PortFast and BPDU Guard on edge ports. The correct fix is to ensure no BPDUs are sent from the downstream device or use 'spanning-tree bpduguard disable' on that port if it is not an edge port (but the task mandates BPDU Guard). Since the scenario requires BPDU Guard, the candidate should recover the port and then verify that the connected device is not a switch (or remove it from the topology).
What should I do if I get this 200-301 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 200-301 questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
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