What is the effect of applying the switchport trunk encapsulation dot1q command to a port on a Cisco Catalyst switch？（）

单项选择题WhichstatementcorrectlydescribestheCiscoimplementationofRSTP？（）

A.PortFast， UplinkFast， and BackboneFast specific configurations are ignored in Rapid PVST mode.
B.RSTP is enabled globally and uses existing STP configuration.
C.Root and alternative ports transition immediately to the forwarding state.
D.Convergence is improved by using sub-second timers for the blocking， listening， learning， and forwarding port states.

多项选择题WhichtwostatementscorrectlydescribeUDLD？（）

A.Unidirectional link detection is achieved through monitoring STP BPDUs.
B.It is recommended that it be enabled globally rather than on an individual port.
C.When an error is detected， normal mode will disable a port.
D.It is recommended that it be enabled in normal mode.
E.It is recommended that it be used with the loop guard feature.

单项选择题WhichstatementcorrectlydescribesenablingBPDUguardonanaccessportthatisalsoenabledforPortFast？（）

A.Upon startup， the port transmits 10 BPDUs. If the port receives a BPDU， PortFast and BPDU guard are disabled on that port and it assumes normal STP operation.
B.The access port ignores any received BPDU.
C.If the port receives a BPDU， it is placed into the error-disable state.
D.BPDU guard is only configured globally and the BPDU filter is required for port-level configuration.

多项选择题WhichtwostatementscorrectlydescribecharacteristicsofthePortFastfeature？（）

A.STP will be disabled on the port.
B.PortFast can also be configured on trunk ports.
C.PortFast is required to enable port-based BPDU guard.
D.PortFast is used for both STP and RSTP host ports.
E.PortFast is used for STP-only host ports.

多项选择题WhichtwoRSTPportrolesincludetheportaspartoftheactivetopology？（）

A.root
B.designated
C.alternate
D.backup
E.forwarding
F.learning