Which of the following authentication services should be replaced with a more secure alternative?

A.
RADIUS

B.
TACACS

C.
TACACS+

D.
XTACACS

Explanation:
Terminal Access Controller Access-Control System (TACACS) is less secure than XTACACS,
which is a proprietary extension of TACACS, and less secure than TACACS+, which replaced
TACACS and XTACACS.