Which protocol is the standard for remote authentication and accounting in network access control?

• A. RADIUS authentication protocol
• B. TACACS+ protocol
• C. RADIUS
• D. Diameter protocol

Answer: (C)

RADIUS is the protocol used to provide remote authentication and accounting in network access control. In these setups, a network access server or wireless access point (the authenticator) forwards user credentials to a RADIUS server, which validates them against a directory or database and responds with access decisions. It also collects accounting data about sessions for auditing and billing. This centralized AAA function is why RADIUS has become the standard choice for remote authentication and accounting across many networks, especially when using 802.1X for network access.

TACACS+ focuses more on device administration AAA and uses TCP with heavier encryption for the transport, so it isn’t the default standard for general network access control. Diameter is a newer, more feature-rich protocol that can replace RADIUS in some deployments, but RADIUS remains the widely adopted standard for remote user authentication and accounting in many environments.