Typically，an IP address refers to an individual host on aparticular 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（1）group is referred to as multicasting. Multicasting done（2）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（3）multicast group recognize the multicast addressand（4）the packet. In this case，only a single copy of the packet is ever transmitted. This technique works because of the（5）nature of a LAN：A transmission from any one station is received by all othe rstation on the LAN.