What is the outcome when RPF check passes successfully?

What is the outcome when RPF check passes successfully?
A . Packet is dropped because it arrived on the interface that used to forward the packet back to source.
B . Packet is dropped because it arrived on the interface that used to forward the packet back to destination.
C . Packet is forwarded because it arrived on the interface that used to forward the packet back to destination
D . Packet is forwarded because it arrived on the interface that used to forward the packet back to source

View Answer

Answer: D

Explanation:

Routers perform a reverse path forwarding (RPF) check to ensure that arriving multicast packets were received through the interface that is on the most direct path to the source that sent the packets. An RPF check is always performed regarding the incoming interface, which is considered to be the RPF interface. The RPF check will succeed if the incoming interface is the shortest path to the source. The router determines the RPF interface by the underlying unicast routing protocol or the dedicated multicast routing

protocol in cases where one exists. An example of a dedicated multicast routing protocol is MP-BGP. It is important to note that the multicast routing protocol relies on the underlying unicast routing table. Any change in the unicast routing table immediately triggers an RPF recheck on most modern routers.