What is a multicast address used for?

A multicast address is used to send a single packet to multiple hosts at once efficiently. This is particularly useful in scenarios where a data stream, such as video or audio, needs to be distributed to several recipients without sending separate copies of the same packet to each host. By using multicast addresses, the sender only sends one copy of the packet which is then duplicated by the network switches as needed, significantly reducing network bandwidth usage.

In contrast, sending packets to all hosts in a network refers more to broadcast addresses, where a message is sent to every device on the network. Sending packets to a specific host involves the use of a unicast address, where the data is directed to one particular device. The option regarding reserving an IP address does not pertain to the function of a multicast address, as multicast addresses serve the purpose of simultaneous communication with multiple hosts.