Cisco Certified Network Associate (CCNA) Practice Exam

What is the command to enable Backbone Fast on a switch?

1. (config)#spanning-tree backbonefast

2. (config)#backbone fast enable

3. (config)#enable backbonefast

4. (config)#spanning-tree mode backbone-fast

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

The command to enable Backbone Fast on a switch is correctly identified as spanning-tree backbonefast. This command is part of the spanning tree protocol configurations and is specifically designed to help switches avoid latency in network convergence when a link failure occurs. By enabling Backbone Fast, the switch can quickly re-route traffic, enhancing overall network efficiency. Other options do not represent correct syntax or command structure for enabling Backbone Fast. Some may resemble features from different network settings or lack the necessary protocol prefix, which is critical for the switch to interpret the command accurately in the context of spanning tree protocol configurations.