Implementing and Operating Cisco Data Center Core Technologies (DCCOR) — Question 118

An engineer need to implement a solution that prevents loops from occurring accidentally by connecting a switch to interface Ethernet1/1. The port is designated to be used for host connectivity. Which configuration should be implemented?

Answer options

• A. switch# configure terminal switch(config)# interface Ethernet1/1 switch(config-if)# spanning-tree bpduguard enable
• B. switch# configure terminal switch(config)# interface Ethernet1/1 switch(config-if)# spanning-tree guard loop
• C. switch# configure terminal switch(config)# interface Ethernet1/1 switch(config-if)# spanning-tree loopguard default
• D. switch# configure terminal switch(config)# interface Ethernet1/1 switch(config-if)# spanning-tree bpdufilter enable

Correct answer: A

Explanation

The correct answer is A, as enabling BPDU guard on the port prevents loops by shutting down the port if any Bridge Protocol Data Units (BPDUs) are received, which is critical for host ports. Option B is incorrect because 'spanning-tree guard loop' does not provide the same protection against loops as BPDU guard. Option C, 'spanning-tree loopguard default', is not effective for host ports and is used for preventing a loop condition in a topology. Option D, 'spanning-tree bpdufilter enable', allows BPDUs to be filtered, which could lead to loops if misconfigured.