Home » Cisco » 642-661 » Which forward mechanism pre-builds the complete IP forwarding table (FIB) based on the IP routing table?
Which forward mechanism pre-builds the complete IP forwarding table (FIB) based on the IP routing table?
A. CEF Switching
B. Fast Switching
C. Process Switching
D. Optimum Switching
Correct Answer: A
Explanation/Reference:
Explanation: CEF is the most advanced form and build a separate FIB. Cisco Express Forwarding (CEF) pre-builds complete IP forwarding table (called Forwarding Information Base or FIB) based on IP routing table. Once an entry is installed in the routing table, due to incoming routing information updates, the recursive lookup is done, and the outgoing interface and the actual physical next-hop are determined. MAC address resolution and MAC header generation are still traffic-driven and stored in the cache.
Reference: Configuring BGP on Cisco routers p.4-32
