单项选择题 Whiletroubleshootingaconnectivityproblem,anetworkadministratornoticesthataportstatusLEDonaCiscoCatalystseriesswitchisalternatinggreenandamber.Whichconditioncouldthisindicate?（）

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?（）