多项选择题
A.BPDU port-guard can be enabled globally， whereas BPDU filtering must be enabled on a per-interface basis.
B.When globally enabled， BPDU port-guard and BPDU filtering apply only to PortFast enabled ports.
C.When globally enabled， BPDU port-guard and BPDU filtering apply only to trunking-enabled ports.
D.When a BPDU is received on a BPDU port-guard enabled port， the interface goes into the err-disabled state.
E.When a BPDU is received on a BPDU filtering enabled port， the interface goes into the err-disabled state.
F.When a BPDU is received on a BPDU filtering enabled port， the interface goes into the STP blocking state.
单项选择题 Refer to the exhibit and the partial configuration of switch SW_A and SW_B. STP is configured on all switches in the network. SW_B receives this error message on the console port： 00：06：34： %CDP-4-DUPLEX_MISMATCH： duplex mismatch discovered on FastEthernet0/5 （not half duplex）， with SW_A FastEthernet0/4 （half duplex） ， with TBA05071417（Cat6K-B） 0/4 （half duplex）. What would be the possible outcome of the problem？（）
多项选择题 WhichtwostatementsaboutthevariousimplementationsofSTParetrue？（）
单项选择题 Refer to the exhibit. For what purpose is the command show ip cef used？（）