AnytimeahostorarouterhasanIPdatagramtosendtoanotherhostorrouter,ithasthe()addressofthereceiver.ThisaddressisobtainedfromtheDNSifthesenderisthehostoritisfoundinaroutingtableifthesenderisarouter.ButtheIPdatagrammustbe()inaframetobeabletopassthroughthephysicalnetwork.Thismeansthatthesenderneedsthe()addressofthereceiver.ThehostortheroutersendsanARPquerypacket.ThepacketincludesthephysicalandIPaddressesofthesenderandtheIPaddressofthereceiver.Becausethesenderdoesnotknowthephysicaladdressofthereceiver,thequeryis()overthenetwork.EveryhostorrouteronthenetworkreceivesandprocessestheARPquerypacket,butonlytheintendedrecipientrecognizesitsIPaddressandsendsbackanARPresponsepacket.Theresponsepacketcontainstherecipient'sIPandphysicaladdresses.Thepacketis(请作答此空)directlytotheinquirerbyusingthephysicaladdressreceivedinthequerypacket.
A.multicast
B.unicast
C.broadcast
D.multiple unicast
正确答案是B