Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) — Question 30

What is the difference between a RIB and a FIB?

Answer options

• A. The FIB is populated based on RIB content.
• B. The RIB maintains a mirror image of the FIB.
• C. The RIB is used to make IP source prefix-based switching decisions.
• D. The FIB is where all IP routing information is stored.

Correct answer: A

Explanation

The correct answer is A because the Forwarding Information Base (FIB) is derived from the Routing Information Base (RIB) and reflects the best routes for forwarding packets. Options B and D are incorrect as the RIB does not mirror the FIB and the FIB does not store all routing information, but rather contains only the routes selected for forwarding. Option C is misleading since the RIB is not primarily used for IP source prefix-based switching decisions.