Debugging cached CEF adjacencies

A while ago I wrote about cached CEF adjacencies and the impact they have on ARP caching. If you ever need to, you can debug them with the debug ip cef table command. As this command might produce a lot of output in a production network, always use it in combination with an access-list that limits the debugging to the selected address range.

Alternatively, you can use the debug arp adjacency command, but you cannot limit its output with an access-list

For example, to test cached CEF adjacencies in subnet, I've used the following commands:
rtr#show ip access-list 99
Standard IP access list 99
10 permit, wildcard bits (26 matches)
rtr#debug ip cef table 99
IP CEF table debugging is on for access list 99
rtr#debug arp
ARP packet debugging is on

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:

08:57:27: IP ARP: creating incomplete entry for IP address: interface FastE
08:57:27: IP ARP: sent req src 0016.c876.8b38,
dst 0000.0000.0000 FastEthernet0/0
08:57:27: IP ARP: rcvd rep src 000c.29a7.8ade, dst FastEthernet0/0
08:57:27: CEF-IP: Checking dependencies of
08:57:27: CEF-Table: Adjacency-prefix add request -- succee
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/4 ms
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