Designing Cisco Enterprise Networks (ENSLD) — Question 252

What is the purpose of the RPF check in multicast routing?

Answer options

• A. to ensure that multicast packets are forwarded if they arrived on the interface used to route traffic back to the source address
• B. to ensure that multicast packets are dropped if they arrived on the interface used to route traffic to the destination address
• C. to ensure that multicast packets are forwarded if they arrived on the interface used to route traffic to the destination address
• D. to ensure that multicast packets are dropped if they arrived on the interface used to route traffic back to the source address
• E. to ensure that multicast packets, no matter the interface they arrived on, are forwarded out all interfaces

Correct answer: A

Explanation

The correct answer is A because the RPF (Reverse Path Forwarding) check is designed to ensure that multicast packets are only forwarded if they arrive on the interface that is used to reach the source address. Options B, C, and D incorrectly describe the behavior of the RPF check, while option E does not align with the purpose of the RPF mechanism, which is to prevent loops and ensure proper routing paths.