Q & A on Broadcast mand Multicast Q: I do not believe I understand the difference between broadcasting & multicasting. As far as I can tell, both require the CPU to make a decision, do I want to listen. How is multicasting better? A: Although you are correct that each station on a LAN must make a decision, the difference between broadcasting and multicasting lies in how that decision is made. Broadcast A network interface card accepts each broadcast frame and passes it to the operating system. The CPU, executing protocol software, is used to decide whether to accept and process the frame. Multicast Instead of using the CPU to handle each frame, the CPU is only used to configure the network interface card. The NIC is given a specific list of multicast addressess to accept. If a frame matches any of the specifed addresses, the station's unicast address, or the broadcast address, the NIC accepts the frame; otherwise, the NIC rejects the frame. In particular, the NIC rejects any frame sent to a multicast address that is not in its list. Thus, the NIC hardware is used to make the decision rather than the CPU.