Cisco Certified Network Associate (CCNA) Practice Exam

Which command enables PortFast on all non-trunking ports?

1. spanning-tree portfast default

2. spanning-tree portfast

3. spanning-tree bpduguard enable

4. spanning-tree portfast bpduguard default

The correct answer is: spanning-tree portfast default

The command that enables PortFast on all non-trunking ports is "spanning-tree portfast default." This command allows for the configuration of PortFast globally on all switch ports that are designated as access ports, meaning they do not participate in trunking. By enabling PortFast, the ports immediately transition to the forwarding state, bypassing the usual listening and learning states of the Spanning Tree Protocol (STP). This is especially useful for ports that connect to end devices, such as computers or printers, where rapid connectivity is desired. Other commands related to spanning tree, such as enabling BPDU guard or simply enabling PortFast without the "default" parameter, do not affect all non-trunking ports globally in the same way. The global configuration ensures that any non-trunking port on the switch will have PortFast enabled automatically without having to configure each port individually. This streamlines network setup and enhances performance for devices requiring quick access to the network.