What is the best way to confirm that AAA authentication is working properly?

A.
Use the test aaa command.

B.
Ping the NAS to confirm connectivity.

C.
Use the Cisco-recommended configuration for AAA authentication.

D.
Log into and out of the router, and then check the NAS authentication log.

Explanation:
BD
#test aaa group tacacs+ admin cisco123 legacy – A llow verification of the authentication function working
between the AAA client (the router) and the ACS server (the AAA server).
Source: Cisco Official Certification Guide, Table 3-6 Command Reference, p.68