How does Cisco Express Forwarding (CEF) switching differ from process switching on Cisco devices?

Cisco Express Forwarding (CEF) switching is a high-performance, hardware-accelerated forwarding mechanism that utilizes dedicated hardware processors (ASICs) to make forwarding decisions. This allows for very fast packet forwarding, as the CPU is not involved in every packet's forwarding path. Process switching, in contrast, is the slowest forwarding method where every packet is processed by the main CPU. The CPU looks up the destination in the routing table, applies any necessary security policies, and then forwards the packet. This is CPU-intensive and significantly slower than CEF. The first incorrect option is wrong because CEF stores forwarding information (FIB and adjacency tables) in the data plane (often in specialized memory on line cards), but process switching also uses main memory for its routing table lookups. The second option is incorrect because CEF builds its adjacency tables from the routing table and ARP information, not CDP. Process switching also uses the routing table. The fourth option is incorrect as CEF does not use a proprietary protocol based on IS-IS for MAC address lookup; it uses the FIB and adjacency tables derived from routing and ARP. Process switching uses the routing table and ARP for MAC resolution.