You are the administrator of a switch and currently all host-connected ports are configured with the
portfast command. You have received a new directive from your manager that states that, in the
future, any host-connected port that receives a BPDU should automatically disable PortFast and
begin transmitting BPDUs. Which command will support this new requirement?

A.
Switch(config)#spanning-tree portfast bpduguard default

B.
Switch(config-if)#spanning-tree bpduguard enable

C.
Switch(config-if)#spanning-tree bpdufilter enable

D.
Switch(config)#spanning-tree portfast bpdufilter default

Explanation:
When spanning-tree bpdufilter enable either on interface configuration or on global configuration
mode prevents from sending or receiving Bridge Protocol Data Units on portfast enabled interface.
To enable bpdufilter global configuration mode:
Device1(Config)#spanning-tree portfast bpdufilter default
Be careful when enabling BPDU filtering. Functionality is different when enabling on a per-port
basis or globally. When enabled globally, BPDU filtering is applied only on ports that are in an
operational PortFast state. Ports still send a few BPDUs at linkup before they effectively filter
outbound BPDUs. If a BPDU is received on an edge port, it immediately loses its operational
PortFast status and BPDU filtering is disabled.
Reference:
http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.1E/native/command/reference/
S1.html#wp1180453