Which two of these are characteristics of multicast routing？ （）

• A、 multicast routing uses RPF
• B、 multicast routing is connectionless.
• C、 In multicast routing， the source of a packet is known.
• D、 When network topologies change， multicast distribution trees are not rebuilt， but use the originalpath
• E、 Multicast routing is much like unicast routing， with the only difference being that it has a a groupof receivers rather than just one destination