CCNA Switching and Network Access Practice Question
Network Topology
You are connected to R1, a Catalyst 3650 multilayer switch running IOS-XE. Configure Root Guard on all designated ports, Loop Guard on uplink interfaces, and BPDU Guard on all PortFast-enabled ports. Troubleshoot the current issue: one port is receiving a superior BPDU and is being blocked by Root Guard, and a different PortFast port has gone err-disabled after BPDU Guard triggered. Verify that Root Guard is active on port Gi1/0/1, Loop Guard is active on Gi1/0/2, and BPDU Guard is enabled on Gi1/0/3.
⚠ Common exam trap
Be careful not to confuse the purpose of Root Guard and Loop Guard. Root Guard is for designated ports, Loop Guard is for root/alternate ports. Also, remember that an err-disabled port requires a shutdown/no shutdown sequence to recover, not just no shutdown.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Remove Root Guard from Gi1/0/1 and apply it to Gi1/0/2; remove Loop Guard from Gi1/0/2 and apply it to Gi1/0/1; on Gi1/0/3, issue shutdown then no shutdown; verify Root Guard on Gi1/0/2, Loop Guard on Gi1/0/1, BPDU Guard on Gi1/0/3.
The network requires Root Guard on designated ports, Loop Guard on uplink (root/alternate) ports, and BPDU Guard on PortFast ports. Gi1/0/1 is receiving a superior BPDU and being blocked by Root Guard, indicating Root Guard is misapplied to a non-designated port; it should be moved to the designated port Gi1/0/2. Loop Guard belongs on the uplink port Gi1/0/1, not Gi1/0/2, so the configuration is swapped. The PortFast port Gi1/0/3 experienced a BPDU Guard violation and is err-disabled; recovering it requires a shutdown followed by a no shutdown command, not just no shutdown. Finally, verification must confirm the correct new placement: Root Guard on Gi1/0/2, Loop Guard on Gi1/0/1, and BPDU Guard on Gi1/0/3.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Remove Root Guard from Gi1/0/1 and apply it to Gi1/0/2; remove Loop Guard from Gi1/0/2 and apply it to Gi1/0/1; on Gi1/0/3, issue shutdown then no shutdown; verify Root Guard on Gi1/0/2, Loop Guard on Gi1/0/1, BPDU Guard on Gi1/0/3.
Why this is correct
Root Guard should be applied to designated ports to prevent them from becoming root ports. Since Gi1/0/1 is receiving a superior BPDU, it is not a designated port; Root Guard should be on Gi1/0/2, the designated port. Loop Guard is intended for root ports or alternate root ports; Gi1/0/2 is not a root port, so Loop Guard should be on Gi1/0/1, the uplink. BPDU Guard err-disabled Gi1/0/3; after ensuring no BPDUs, the port must be brought up with shutdown/no shutdown. Verification commands confirm the correct configuration.
- ✗
Remove Root Guard from Gi1/0/1 and apply it to Gi1/0/2; remove Loop Guard from Gi1/0/2 and apply it to Gi1/0/1; on Gi1/0/3, issue no shutdown; verify Root Guard on Gi1/0/2, Loop Guard on Gi1/0/1, BPDU Guard on Gi1/0/3.
Why it's wrong here
Attempting to recover an err-disabled port with only "no shutdown" is insufficient; when BPDU Guard err-disables Gi1/0/3, the interface must first be administratively shut down with "shutdown" and then re-enabled with "no shutdown" to clear the error-disabled state. While the Root Guard and Loop Guard placement in this option is correct, the recovery procedure fails because a single "no shutdown" does not override err-disabled status. As a result, the port remains out of service, and the verification step would not confirm BPDU Guard as operationally active.
- ✗
Remove Root Guard from Gi1/0/1 and apply it to Gi1/0/2; remove Loop Guard from Gi1/0/2 and apply it to Gi1/0/1; on Gi1/0/3, issue shutdown then no shutdown; verify Root Guard on Gi1/0/1, Loop Guard on Gi1/0/2, BPDU Guard on Gi1/0/3.
Why it's wrong here
The configuration changes for Root Guard and Loop Guard are correct, but the verification step checks the wrong interfaces: Root Guard must be verified on Gi1/0/2, which is the designated port, and Loop Guard must be verified on Gi1/0/1, which is the root/alternate port. By checking Root Guard on Gi1/0/1 and Loop Guard on Gi1/0/2, this option would not validate the protections that were just applied, leaving the network potentially misconfigured without detection. A proper verification must align with the port roles that each guard is designed to protect.
- ✗
Remove Root Guard from Gi1/0/1 and apply it to Gi1/0/2; remove Loop Guard from Gi1/0/2 and apply it to Gi1/0/1; on Gi1/0/3, issue shutdown then no shutdown; verify Root Guard on Gi1/0/2, Loop Guard on Gi1/0/2, BPDU Guard on Gi1/0/3.
Why it's wrong here
This option appears identical to the correct answer but is actually a trick; however, based on the given options, it is not marked as correct. The correct answer is A, and D is a duplicate. Since the question requires exactly one correct answer, D is considered incorrect.
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.
✓Remove Root Guard from Gi1/0/1 and apply it to Gi1/0/2; remove Loop Guard from Gi1/0/2 and apply it to Gi1/0/1; on Gi1/0/3, issue shutdown then no shutdown; verify Root Guard on Gi1/0/2, Loop Guard on Gi1/0/1, BPDU Guard on Gi1/0/3.Correct answer▾
Why this is correct
Root Guard should be applied to designated ports to prevent them from becoming root ports. Since Gi1/0/1 is receiving a superior BPDU, it is not a designated port; Root Guard should be on Gi1/0/2, the designated port. Loop Guard is intended for root ports or alternate root ports; Gi1/0/2 is not a root port, so Loop Guard should be on Gi1/0/1, the uplink. BPDU Guard err-disabled Gi1/0/3; after ensuring no BPDUs, the port must be brought up with shutdown/no shutdown. Verification commands confirm the correct configuration.
✗Remove Root Guard from Gi1/0/1 and apply it to Gi1/0/2; remove Loop Guard from Gi1/0/2 and apply it to Gi1/0/1; on Gi1/0/3, issue no shutdown; verify Root Guard on Gi1/0/2, Loop Guard on Gi1/0/1, BPDU Guard on Gi1/0/3.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that an err-disabled port cannot be recovered with a single 'no shutdown' command; the correct procedure is to issue 'shutdown' then 'no shutdown'.
Why candidates choose this
Candidates may think that 'no shutdown' alone is sufficient to bring an err-disabled port back up, but the port must first be placed in shutdown state to clear the error condition.
✗Remove Root Guard from Gi1/0/1 and apply it to Gi1/0/2; remove Loop Guard from Gi1/0/2 and apply it to Gi1/0/1; on Gi1/0/3, issue shutdown then no shutdown; verify Root Guard on Gi1/0/1, Loop Guard on Gi1/0/2, BPDU Guard on Gi1/0/3.Wrong answer — click to see why▾
Why this is wrong here
The specific factual error is that after reconfiguration, Root Guard is on Gi1/0/2 and Loop Guard is on Gi1/0/1, but the verification commands target the original ports, which would show incorrect status.
Why candidates choose this
Candidates might assume that verification should be done on the ports that originally had issues, but the correct verification must match the new configuration.
✗Remove Root Guard from Gi1/0/1 and apply it to Gi1/0/2; remove Loop Guard from Gi1/0/2 and apply it to Gi1/0/1; on Gi1/0/3, issue shutdown then no shutdown; verify Root Guard on Gi1/0/2, Loop Guard on Gi1/0/2, BPDU Guard on Gi1/0/3.Wrong answer — click to see why▾
Why this is wrong here
The verification step incorrectly claims Loop Guard is on Gi1/0/2 after the swap; Loop Guard was moved to Gi1/0/1, so this option validates the wrong port.
Why candidates choose this
Candidates may be confused by duplicate options and might think both are correct, but only one is designated as correct.
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?”
Visual reference
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Related to this question
Learn chapter
Configuring Switch Ports for Desktops, VoIP Phones, APs, IoT, and Virtualized Hosts
Key term
BPDU
A Bridge Protocol Data Unit is a layer 2 frame that switches use to exchange information about the Spanning Tree Protocol (STP) to prevent network loops.
Key term
Designated port
In a Spanning Tree Protocol network, a Designated port is the port on a network segment that has the best path to the root bridge and is responsible for forwarding traffic toward the root bridge.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.