Implementing Cisco IP Routing (CCNP ROUTE, legacy) — Question 12

When unicast reverse path forwarding is configured on an interface, which action does the interface take first when it receives a packet?

Answer options

• A. It verifies that the source has a valid CEF adjacency.
• B. It checks the egress access lists.
• C. It verifies a reverse path via the FIB to the source.
• D. It checks the ingress access lists.

Correct answer: C

Explanation

The correct answer is C, as the primary function of unicast reverse path forwarding is to ensure that the incoming packets originate from a valid source by verifying the reverse path via the FIB. Options A and D relate to adjacency and access list checks that are not the first actions taken, while option B pertains to egress access lists, which are not involved in the initial packet reception process.