单项选择题
A.The port is experiencing errors.
B.The port is administratively disabled.
C.The port is blocked by spanning tree.
D.The port has an active link with normal traffic activity.
单项选择题 Onpoint-to-pointnetworks,OSPFhellopacketsareaddressedtowhichaddress?（）
单项选择题 In order to allow the establishment of a Telnet session with a router, which set of commands must be configured?（）
单项选择题 Whiletroubleshootinganetworkconnectivityproblem,atechnicianobservessteadylinklightsonboththeworkstationNICandtheswitchporttowhichtheworkstationisconnected.However,whenthepingcommandisissuedfromtheworkstation,theoutputmessage"Requesttimedout."isdisplayed.AtwhichlayeroftheOSImodeldoestheproblemmostlikelyexist?（）