单项选择题
A. The packet will loop between R1 and R2.
B. It is not possible to set the administrative distance on a summary to 255.
C. The packet will be forwarded to R2， where it will be routed to null0.
D. The packet will be dropped by R1， since there is no route to 192.168.3.1.
单项选择题 YouarethenetworkadministratorofasmallLayer2networkwith50users.Lately，usershavebeencomplainingthatthenetworkisveryslow.Whiletroubleshooting，younoticethattheCAMtableofyourswitchisfull，althoughitsupportsupto12，000MACaddresses.Howcanyousolvethisissueandpreventitfromhappeninginthefuture？（）
单项选择题 TworoutersconfiguredtorunBGPhavebeenconnectedtoafirewall，oneontheinsideinterfaceandoneontheoutsideinterface.BGPhasbeenconfiguredsothetworoutersshouldpeer，includingthecorrectBGPsessionendpointaddressesandthecorrectBGPsessionhop-countlimit（EBGPmultihop）.WhatisagoodfirsttesttoseeifBGPwillworkacrossthefirewall？（）
多项选择题 Youarethenetworkadministratorofamedium-sizedcompany，andusersarecomplainingthattheycannotsendemailstosomeorganizations.Duringyourtroubleshooting，younoticethatyourDNSMXrecordisblacklistedbyseveralpublicblacklistfilters.AfterclearingtheselistingsforyourIPaddress，andassumingthatyouremailserverhastherightvirusprotectioninplace，whataretwopossiblesolutionstopreventthisfromhappeninginthefuture？（）
