Which of the following commands can be issued without interfering with the operation of loop guard？（）

单项选择题A port in a redundant topology is currently in the blocking state and is not receiving BPDUs. To ensure that this port does not erroneously transition to the forwarding state，  which command should be configured to satisfy the requirement？（）

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

单项选择题Whichspanning-treecommandwouldcauseaPortFast-enabledinterfacetoloseitsPortFast-operationalstatusanddisableBPDUfilteringifitreceivesBPDUs？（）

A.spanning-tree guard root
B.spanning-tree portfast bpduguard default
C.spanning-tree bpduguard enable
D.spanning-tree bpdufilter enable
E.spanning-tree portfast bpdufilter default

单项选择题Whichofthefollowingconditionsguaranteesthatabroadcaststormcannotoccur？（）

A.a native VLAN mismatch on either side of an 802.1Q link
B.BPDU filter configured on a link to another switch
C.Spanning Tree Protocol enabled on both Layer 2 and multilayer switches
D.PortFast enabled on all access and trunk ports

单项选择题WhichstatementistrueregardingthePortAggregationProtocol？（）

A.Configuration changes made on the port-channel interface apply to all physical ports assigned to the portchannel interface.
B.Configuration changes made on a physical port that is a member of a port-channel interface apply to the port-channel interface.
C.Configuration changes are not permitted with Port Aggregation Protocol； instead， the standardized Link Aggregation Control Protocol should be used if configuration changes are required.
D.The physical port must first be disassociated from the port-channel interface before any configuration changes can be made.

单项选择题WhichcommandalonewilldisabletrunkingonaLayer2switchport？（）

A.no switchport trunk native vlan vlan-id
B.switchport nonegotiate
C.no switchport mode dynamic desirable
D.switchport mode access