Typically，an IP address refers to an individual host on a particular network. IP also accommodates addresses that refer to a group of hosts on one or more networks.Sunch addresses are referred to as multicast addresses，and the act of sending a packet from a source to the members of a （71）group is referred to as multicasting. Multicasting done (72 ) the scope of a single LAN segment is straightforward. IEEE 802 and other LAN protocols include provision for MAC-level multicast addresses. A packet with a multicast address is transmitted on a LAN segment.Those stations that are members of the （73）multicast group recognize the multicast address and （74）the packet.In this case,only a single copy of the packet is ever transmitted.This technique works because of the （75）nature of a LAN:A transmission from any one station is received by all other stations on the LAN.
71、A.numerous
B.only
C.single
D.multicast
72、A.within
B.out of
C.beyond
D.cover
73、A.different
B.unique
C.special
D.corresponding
74、A.reject
B.accept
C.discard
D.transmit
75、A.multicast
B.unicast
C.broadcast
D.multiple unicast