In Frame Relay， FECN messages indicating congestion are sent or received by which of following？（）

单项选择题Priorto802.1w，Ciscoimplementedanumberofproprietaryenhancementsto802.1DtoimproveconvergenceinaLayer2network.Whichstatementiscorrect？（）

A.Only UplinkFast and BackboneFast are specified in 802.1w； PortFast must be manually configured.
B.Only PortFast is specified in 802.1w； UplinkFast and BackboneFast must be manually configured.
C.None of the proprietary Cisco enhancements are specified in 802.1w.
D.PortFast， UplinkFast， and BackboneFast are specified in 802.1w.

单项选择题Auserhasnonetworkconnectivity.Acheckoftheassociatedportindicatesthattheinterfaceisup，thelineprotocolisdown.Whichitemwouldmostlikelycausethisproblem？（）

A.Speed mismatch
B.Incorrect encapsulation
C.MTU set too low
D.Duplex mismatch

单项选择题Youworkasanetworkengineerforthecompany，youwanttoconfiguretwoBGPspeakerstoformanEBGPsessionacrossafirewall.Ontheengineer’snetwork，thefirewallalwayspermitsTCPsessionsthatareinitiatedfromtheinsidenetwork（thenetworkattachedtotheinsideinterfaceofthefirewall）.WhatprerequisiteisthereforenablingBGPtorunonthisnetwork？（）

A.EBGP multihop will need to be configured for this to work.
B.This should work with normal BGP peering， with no additional configuration on the BGP speakers or the firewall.
C.The BGP protocol port must be opened on the firewall
D.There is no way to make BGP work across a firewall.

单项选择题MultiProtocolLabelSwitching（MPLS）isadata-carryingmechanismthatbelongstothefamilyofpacket-switchednetworks.ForanMPLSlabel，ifthestackbitissetto1，whichoptionistrue？（）

A.The stack bit will only be used when LDP is the label distribution protocol
B.The label is the last entry in the label stack.
C.The stack bit is for Cisco implementations exclusively and will only be used when TDP is the label distribution protocol.
D.The stack bit is reserved for future use.

单项选择题TheOSPFRFC3623GracefulRestartfeatureallowsyoutoconfigureIETFNSFinultivendornetworks.WhenusingOSPFGracefulRestart，whichmechanismisusedtocontinueforwardingpacketsduringaswitchover？（）

A.Reverse Path Forwarding
B.Hardware-based forwarding
C.UDP forwarding
D.Layer 2 Forwarding