Which spanning-tree command would cause a PortFast-enabled interface to lose its PortFast-operational status and disable BPDU filtering if it receives BPDUs？（）

A . They have been configured with the spanning-tree bpdufilter disable command. B . They have been configured with the spanning-tree bpdufilter enable command. C . They have been configured with the spanning-tree bpduguard disable command. D . They have been configured with the spanning-tree bpduguard enable command. E . They have been configured with the spanning-tree guard loop command. F . They have been configured with the spanning-tree guard root command.

A . All switch and bridge ports are in the forwarding state. B . All switch and bridge ports are assigned as either root or designated ports. C . All switch and bridge ports are in either the forwarding or blocking state. D . All switch and bridge ports are either blocking or looping.

A . A、网络瘫痪 B . B、产生广播风暴 C . C、产生丢包 D . D、无影响

A . Combine all the VLAN spanning trees into a single spanning tree B . Set forward delay and max-age timers to the maximum possible values C . None of the choices D . Change the router VTP server mode E . Disable the root bridge

A . redundant B . spanned C . provisioned D . converged

A . BPDUs will be sent out every two seconds. B . The time spent in the listening state will be 30 seconds. C . The time spent in the learning state will be 15 seconds. D . The maximum length of time that the BPDU information will be saved is 30 seconds. E . This switch is the root bridge for VLAN 200. F . BPDUs will be sent out every 10 seconds.

A . path cost B . lowest port MAC address C . VTP revision number D . highest port priority number E . port priority number and MAC addre

A . PortFast B . UplinkFast C . loop guard D . root guard E . BPDU guard F . BackboneFast

A . in order to optimize the path that frames take from source to destination B . to increase the priority so a designated port will become a root port C . to increase the BID, so the switch is more likely to become root bridge D . in order to allow VLANs to be sent from one switch to another across a single link E . to force a given switch to become an STP server

A . Switch SW1 has been configured with the spanning-tree vlan 1 root primary global configuration command. B . Switch SW1 has been configured with the spanning-tree vlan 1 root secondary global configuration command. C . Switch SW1 has been configured with the spanning-tree vlan 1 priority 24577 global configuration command. D . Switch SW1 has been configured with the spanning-tree vlan 1 hello-time 2 global configuration command. E . The root bridge has been configured with the spanning-tree vlan 1 root secondary global configuration command.

A . Switch3 B . Switch4 C . Switch2 D . Switch1

A . Switches S1 and S3 will be able to exchange traffic but neither will be able to exchange traffic with Switch S2 B . Switches S1， S2， and S3 will be able to pass traffic between themselves. However， if there is a topology change， Switch S2 will not receive notification of the change. C . Switches S1， S2， and S3 will be able to pass traffic between themselves. D . IEEE 802.1D and IEEE 802.1w are incompatible. All three switches must use the same standard or no traffic will pass between any of the switches.

A .  Spanning tree protect B .  Root Guard and BPDU Guard C .  Unicast Reverse Path Forwarding D .  MAC spoof guard E .  Port Security

A . 32768 B . 23571 C . 128 D . 1 E . 256

A . If BPDUs are received by a port configured for PortFast， they are ignored and none are sent. B . The command will enable BPDU filtering on all ports regardless of whether they are configured for BPDU filtering at the interface level. C . If BPDUs are received by a port configured for Portfast， the port will transition to forwarding state. D . If BPDUs are received by a port configured for PortFast， then PortFast is disabled and the BPDUs are processed normally. E . None of the other alternatives apply.

A . It is the individual link cost based on latency B . It is the sum of the costs based on bandwidth C . It is the total hop count D . It is dynamically determined based on load

A . Switch1 B . Switch2 C . Switch3 D . Switch4

A . BPDU guard can be used to prevent invalid BPDUs from propagating throughout the network.  B . BPDU guard can guarantee proper selection of the root bridge. C . BPDU guard can be utilized to prevent the switch from transmitteing BPDUs and incorrectly altering the root bridge election. D . BPDU guard can be utilized along with PortFast to shut down ports when a switch is connected to the port. E . None of the other alternatives apply

A . 接口FastEthernet0/1 B . Fa0/1 C . 接口Fa0/1 D . 接口E0/1

A . BPDUs that enter a blocking port are discarded. B . BPDUs that enter a blocking port are processed. C . Loopguard puts an interface into a loop-inconsistent state when BPDUs stop being received on a blocking port. D . BPDUs are only processed on forwarding ports.

A . lowest root bridge ID B . lowest path cost to root bridge C . lowest sender bridge ID D . highest port ID E . highest root bridge ID F . highest path cost to root bridge

A .  IEEE 802.1s （MST） B .  IEEE 802.1Q （CST） C .  Cisco PVST+ D .  IEEE 802.1d （STP） E .  None of the other alternatives apply

A . the switch with the lowest MAC address B . the switch with the higest MAC address C . the switch witch the higest IP address D . the switch with the lowest IP addre