Refer to the exhibit.
If R1 contacts the RADIUS server but is unable to find the user name in the server database, how will R1 respond?
A. It will deny the user access
B. It will prompt the user to enter a new username
C. It will attempt to authenticate the user against the local database
D. It will attempt to contact the TACACS+ server
https://www.cisco.com/c/en/us/support/docs/security-vpn/terminal-access-controller-access-control-system-tacacs-/200606-aaa-authentication-login-default-local.html
If the RADIUS server is reachable AND the username does not exist, then access will be denied.
If the RADIUS server is NOT reachable, it would move to TACACS+
Correct answer A