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.Such 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.
