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 destinatio
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