The correct configuration requires Root Guard on designated ports, Loop Guard on uplink ports, and BPDU Guard on PortFast-enabled ports, so you must swap the guards on Gi1/0/1 and Gi1/0/2, then recover the err-disabled Gi1/0/3 with a shutdown followed by no shutdown. Root Guard should only be placed on designated ports because it blocks a port from becoming a root port if a superior BPDU is received—if it’s on a non-designated port like Gi1/0/1, it incorrectly blocks the legitimate superior BPDU, whereas Loop Guard belongs on root or alternate uplink ports to prevent loops from missing BPDUs. On the CCNA 200-301 v2 exam, this tests your ability to distinguish guard placement and recover err-disabled ports, with a common trap being that BPDU Guard violations require a full interface cycle (shutdown/no shutdown) rather than just a no shutdown. Remember the mnemonic: “Root on Designated, Loop on Uplink, BPDU on PortFast—swap and cycle to make it last.”
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 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.
R1#show running-config | section interface
interface GigabitEthernet1/0/1
description Link to R2
switchport mode access
spanning-tree guard root
!
interface GigabitEthernet1/0/2
description Uplink to Core
switchport mode trunk
spanning-tree guard loop
!
interface GigabitEthernet1/0/3
description Access Port
switchport mode access
spanning-tree portfast
spanning-tree bpduguard enable
!
R1#show spanning-tree interface Gi1/0/1 detail
Port 1 (GigabitEthernet1/0/1) of VLAN0001 is root blocking
Port path cost 4, Port priority 128, Port Identifier 128.1.
Designated root has priority 0, address aaaa.bbbb.cccc
Designated bridge has priority 4096, address aaaa.bbbb.cccc
Designated port id is 128.1, designated path cost 0
Timers: message age 2, forward delay 15, hold 0
Number of transitions to forwarding state: 0
BPDU: sent 0, received 10
Root guard is enabled, but port is root inconsistent
R1#show spanning-tree interface Gi1/0/2 detail
Port 2 (GigabitEthernet1/0/2) of VLAN0001 is alternate blocking
Port path cost 4, Port priority 128, Port Identifier 128.2.
Designated root has priority 0, address aaaa.bbbb.cccc
Designated bridge has priority 0, address aaaa.bbbb.cccc
Designated port id is 128.2, designated path cost 0
Timers: message age 2, forward delay 15, hold 0
Number of transitions to forwarding state: 0
BPDU: sent 0, received 10
Loop guard is enabled, but port is loop-inconsistent
R1#show interfaces Gi1/0/3 status
Port Name Status Vlan Duplex Speed Type
Gi1/0/3 err-disabled 1 auto auto 10/100/1000BaseTX
A
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.
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.
B
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 wrong: This is incorrect because simply issuing 'no shutdown' on an err-disabled port does not recover it; the port must first be shut down and then brought up with 'shutdown' followed by 'no shutdown'.
C
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 wrong: This is incorrect because the verification step checks the wrong ports. Root Guard should be verified on Gi1/0/2, not Gi1/0/1, and Loop Guard should be verified on Gi1/0/1, not Gi1/0/2.
D
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 wrong: 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.
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.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Related concept
Static NAT maps one inside address to one outside address.
✗
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
This is incorrect because simply issuing 'no shutdown' on an err-disabled port does not recover it; the port must first be shut down and then brought up with 'shutdown' followed by 'no shutdown'.
✗
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
This is incorrect because the verification step checks the wrong ports. Root Guard should be verified on Gi1/0/2, not Gi1/0/1, and Loop Guard should be verified on Gi1/0/1, not Gi1/0/2.
✗
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?”
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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 the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-301 NAT questions on configuration and troubleshooting.
Switching and Network Access — This question tests Switching and Network Access — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this 200-301 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-301 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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