Most central authentication servers are governed by the ________ standard.

• A. EAP
• B. RADIUS
• C. IPsec
• D. 802.1X

Answer: (B)

RADIUS is the protocol designed for centralized authentication, authorization, and accounting in network access scenarios. It sits between network access servers (like VPN concentrators, switches, or wireless controllers) and a centralized authentication server, allowing credentials and policies to be checked in one place. This decouples the authentication process from the network device, enabling consistent access control across diverse services.

EAP is a family of authentication methods often carried inside RADIUS, but it’s not by itself the standard governing central authentication servers. IPsec is a protocol for securing IP communications, not for AAA. 802.1X is a port-based access control framework that uses EAP for authentication, but it relies on an underlying AAA server (often RADIUS) to perform the actual authentication decisions. Therefore, the standard that directly governs central authentication servers is RADIUS.