A network administrator uses the spanning-tree portfast bpduguard default global configuration command to enable BPDU guard on a switch. However, BPDU guard is not activated on all access ports. What is the cause of the issue?
- PortFast is not configured on all access ports.
- Access ports belong to different VLANs.
- BPDU guard needs to be activated in the interface configuration command mode.
- Access ports configured with root guard cannot be configured with BPDU guard.
Answers Explanation & Hints: The most likely cause of the issue is that PortFast is not configured on all access ports. By default, BPDU guard is only enabled on ports with PortFast enabled. Therefore, if PortFast is not enabled on a particular access port, BPDU guard will not be activated on that port even if it is globally enabled with the spanning-tree portfast bpduguard default command. To enable BPDU guard on an access port, the administrator needs to configure PortFast on that port with the spanning-tree portfast interface configuration command.