Which protocol transfers data packets as UDP messages for authentication, authorization, and accounting?

Which protocol transfers data packets as UDP messages for authentication, authorization, and accounting?

• A. Radius
• B. DNS
• C. TCP
• D. ICMP

Answer: (A)

RADIUS is the protocol designed to carry authentication, authorization, and accounting information as UDP datagrams between a network access server and a RADIUS server. It uses UDP as the transport, which makes the exchanges fast and stateless, fitting well with how AAA data is often requested per user session. In practice, you’ll see RADIUS messages sent over UDP on common ports like 1812 for authentication and 1813 for accounting. This UDP, message-based design is what sets RADIUS apart for AAA tasks. By contrast, DNS is mainly for name resolution (though it uses UDP), TCP is a stream-oriented transport used by other AAA protocols like TACACS+ and Diameter, and ICMP serves control and diagnostic purposes rather than authentication/authorization.

RADIUS is the protocol designed to carry authentication, authorization, and accounting information as UDP datagrams between a network access server and a RADIUS server. It uses UDP as the transport, which makes the exchanges fast and stateless, fitting well with how AAA data is often requested per user session. In practice, you’ll see RADIUS messages sent over UDP on common ports like 1812 for authentication and 1813 for accounting. This UDP, message-based design is what sets RADIUS apart for AAA tasks. By contrast, DNS is mainly for name resolution (though it uses UDP), TCP is a stream-oriented transport used by other AAA protocols like TACACS+ and Diameter, and ICMP serves control and diagnostic purposes rather than authentication/authorization.