How does IP multicast differ from IP broadcast?

The distinction between IP multicast and IP broadcast primarily revolves around the targeting of specific devices versus all devices on a network. Multicast traffic is designed to reach a particular group of devices that have expressed interest in receiving the specific data stream. This is achieved by sending packets to specific multicast addresses, which represent groups of devices that have joined a multicast group.

In contrast, broadcast traffic is sent to every device within the given network segment, meaning all devices receive the broadcasted packets regardless of whether they want to or need to receive that information. This can create unnecessary network congestion as all devices are forced to process the broadcast messages.

Therefore, the correct answer highlights the fundamental difference in addressing: multicast targets specific modem addresses (or devices) while broadcast indiscriminately sends data to all devices on the local network.