Enable Fast-Switched PBR

A.

Policy-based routing (PBR) is a mechanism that allows you to selectively route packets based on policies defined by you. Fast-switched PBR refers to the use of the fast-switched path for policy-based routing.

The correct command to enable fast-switched PBR is option A, ip route-cache policy.

Here's a detailed explanation of each answer option:

A. ip route-cache policy: This command enables fast-switched PBR. When you use PBR with this command, the router caches the result of the route lookup in the fast-switching cache. This caching speeds up the processing of subsequent packets that match the same policy.

B. ip policy route-map map-tag: This command enables PBR, but it does not enable fast-switched PBR. When you use PBR with this command, the router performs the route lookup in the main routing table, rather than in the fast-switching cache.

C. no ip route-cache policy: This command disables fast-switched PBR. If you have previously enabled fast-switched PBR, you can use this command to disable it.

D. no ip policy route-map map-tag: This command disables PBR altogether. If you have previously enabled PBR with the ip policy route-map command, you can use this command to disable it.

In summary, to enable fast-switched PBR, use the ip route-cache policy command on the interface where you want to apply the policy.