ICND2: Interconnecting Cisco Networking Devices Part 2 (legacy) — Question 141

Which command do you enter to protect a PortFast-enabled port against unauthorized switches on the network?

Answer options

• A. switch(config)#spanning-tree portfast bpdufilter default
• B. switch(config)#spanning-tree portfast bpduguard default
• C. switch(config-if)#spanning-tree guard root
• D. switch(config-if)#spanning-tree portfast B

Correct answer:

Explanation

The correct command is B, 'switch(config)#spanning-tree portfast bpduguard default', which enables BPDU Guard on the port, preventing unauthorized switches from sending BPDUs. Option A is incorrect because BPDU Filter does not protect against unauthorized switches; it simply suppresses BPDUs. Options C and D are also incorrect as they do not specifically relate to protecting PortFast-enabled ports from unauthorized switches.