Cisco Certified Network Associate (CCNA) Practice Exam

What command is used to enable BPDU Filter in a Cisco switch configuration?

1. (config)#spanning-tree bpdufilter enable

2. (config)#bpdufilter enable

3. (config)#enable bpdufilter

4. (config)#spanning-tree bpdu-filter active

The correct answer is: (config)#spanning-tree bpdufilter enable

The command to enable BPDU Filter in a Cisco switch configuration is indeed the one provided. The syntax accurately reflects Cisco's command-line interface for enabling this feature. BPDU Filter is used to protect the Layer 2 network by preventing Bridge Protocol Data Units (BPDU) from being sent or received on a specific port. By enabling this feature, you can isolate access ports, essentially "filtering" out BPDUs and preventing them from participating in Spanning Tree Protocol (STP) negotiations, thus helping to reduce potential loops in the network. The command using "spanning-tree bpdufilter enable" specifies that the BPDU Filter is being applied specifically within the context of Spanning Tree, which is crucial for managing how traffic is forwarded in a network. This is why the choice provided is the correct command; it represents the proper and complete syntax needed for the feature to be activated on a Cisco device. Using the other options would not result in enabling BPDU Filter as they either misrepresent the command structure or omit crucial components that define its function within the Spanning Tree Protocol context.