Diameter uses which of the following as a base? A. TACACS B. TACACS+ C. RADIUS D. Kerberos Solution C. Diameter uses RADIUS as a base and is considered the next generation of authentication, authorization, and accounting services for the Internet with over 16 million attribute variable pairs (AVP) tags for negotiation. Answer A is incorrect because TACACS is not considered a base for Diameter. Answer B is incorrect because TACACS+ is a Cisco protocol but is widely used. Answer D is incorrect because Kerberos is not associated with Diameter but is considered a single sign-on technology.