Mcast.exe - Windows 2003 Resource Kit Utility
This command-line tool can be used to send multicast packets or to listen for packets being sent to a multicast group address. Mcast is useful for testing whether or not there is multicast connectivity between two computers on your network. This can be done by using Mcast to send packets from one of the computers on your network to the group address you wish to test. On the computer for which you want to test connectivity, you can use Mcast to listen for packets received on the group address. Using this method, you can determine whether or not there is multicast connectivity between the two computers.