Typically,anIPaddressreferstoanindividualhostonaparticularnetwork.IPalsoaccommodatesaddressesthatrefertoagroupofhostsononeormorenetworks.Suchaddressesarereferredtoasmulticastaddresses,andtheactofsendingapacketfromasourcetothemembersofa(1)groupisreferredtoasmulticasting.Multicastingdone(2)thescopeofasingleLANsegmentisstraightforward.IEEE802andotherLANprotocolsincludeprovisionforMAC-levelmulticastaddresses.ApacketwithamulticastaddressistransmittedonaLANSegment.Thosestationsthataremembersofthe(3)multicastgrouprecognizethemulticastaddressand(4)thepacket.Inthiscase,onlyasinglecopyofthepacketisevertransmitted.Thistechniqueworksbecauseofthe(5)natureofaLAN:AtransmissionfromanyonestationisreceivedbyallotherstationontheLAN. 空白(2)应选()。
A.Within
B.out of
C.beyond
D.cover
正确答案是A