Typically，anIPaddressreferstoanindividualhostonaparticularnetwork.IPalsoaccommodatesaddressesthatrefertoagroupofhostsononeormorenetworks.Sunchaddressesarereferredtoasmulticastaddresses，andtheactofsendingapacketfromasourcetothemembersofa(71)groupisreferredtoasmulticasting.Multicastingdone(72)thescopeofasingleLANsegmentisstraightforward.IEEE802andotherLANprotocolsincludeprovisionforMAC-levelmulticastaddresses.ApacketwithamulticastaddressistransmittedonaLANsegment.Thosestationsthataremembersofthe(73)multicastgrouprecognizethemulticastaddressand(74)thepacket.Inthiscase,onlyasinglecopyofthepacketisevertransmitted.Thistechniqueworksbecauseofthe(75)natureofaLAN:AtransmissionfromanyonestationisreceivedbyallotherstationsontheLAN.
A.within
B.out of
C.beyond
D.cover
正确答案是A