Question

What must be configured to enable Cisco Express Forwarding (CEF) on most Cisco devices that perform Layer 3 switching?

1) IP routing
2) IP CEF
3) IP multicast
4) IP unicast

Answer 1

To enable Cisco Express Forwarding (CEF) on Cisco devices, configure IP CEF after ensuring that IP routing is enabled. Enter global configuration mode in the CLI and type 'ip cef' to enable it.

Step-by-step explanation:

To enable Cisco Express Forwarding (CEF) on most Cisco devices that perform Layer 3 switching, you must configure IP CEF. CEF is an advanced layer 3 switching technology used in Cisco routers and switches that provides faster and more scalable IP forwarding by reducing the load on the main CPU.

The basic steps to enable CEF are as follows:

1. Ensure that IP routing is enabled on the device. This is a prerequisite for CEF to work.
2. Enter global configuration mode by typing configure terminal in the device's command-line interface (CLI).
3. Type ip cef or ip cef distributed if the router supports distributed CEF to actually enable CEF on the router.

It is not necessary to configure IP multicast or IP unicast specifically for CEF, as it inherently supports these forwarding methods once enabled.