Multicast applications call an API function on their sockets in order to ask the IP layer to enable or disable reception of packets sent from some specific IP address(es)

to a specific multicast address.

For each of these sockets, the system records the desired multicast reception state. In addition to these per-socket multicast reception states, the system must maintain a multicast reception state for each of its interfaces, which is derived from the per-socket reception states.

Suppose four multicast applications run on the same host, and participate in the same multicast group, M1. The first application uses an EXCLUDE{A1, A2, A3}

filter. The second one uses an EXCLUDE{A1, A3, A4} filter. The third one uses an INCLUDE{A3, A4} filter. And the fourth one uses an INCLUDE{A3} filter. What’s the resulting multicast state (multicast-address, filter-mode, source-list) for the network interface?