单项选择题
A.Address Resolution Protocol (ARP) B.PDU header rewrite C.NetFlow switching D.hello packet exchange
A.Switch(config-if)#spanning-tree guard root B.Switch(config-if)#spanning-tree portfast C.Switch(config-if)#switchport mode trunk D.Switch(config-if)#switchport mode access
A.Switch(config)#spanning-tree loopguard default B.Switch(config-if)#spanning-tree bdpufilter C.Switch(config)#udld aggressive D.Switch(config-if)#spanning-tree bpduguard