单项选择题
A.Sent by the destination
B.Received by the sender
C.Received by the destination
D.Sent by the sender
单项选择题 Priorto802.1w，Ciscoimplementedanumberofproprietaryenhancementsto802.1DtoimproveconvergenceinaLayer2network.Whichstatementiscorrect？（）
单项选择题 Auserhasnonetworkconnectivity.Acheckoftheassociatedportindicatesthattheinterfaceisup，thelineprotocolisdown.Whichitemwouldmostlikelycausethisproblem？（）
单项选择题 Youworkasanetworkengineerforthecompany，youwanttoconfiguretwoBGPspeakerstoformanEBGPsessionacrossafirewall.Ontheengineer’snetwork，thefirewallalwayspermitsTCPsessionsthatareinitiatedfromtheinsidenetwork（thenetworkattachedtotheinsideinterfaceofthefirewall）.WhatprerequisiteisthereforenablingBGPtorunonthisnetwork？（）