For example, the lookup service uses unicast to reply to multicast requests. It acquired the address of the server through the multicast request. Unicast is also helpful when the lookup service is not on the local-area network and could not be reached by multicast. In this case, the user must provide the address of the lookup service. Multicast announcement Multicast announcements are used by lookup services to announce their presence on the network when they are first connected.
Servers reply with a unicast request.
Figure 3 illustrates a multicast announcement. A multicast announcement. Copyright 2001 INT Media Group, Incorporated All Rights Reserved.