Which port number is used by RADIUS for accounting?

Which port number is used by RADIUS for accounting?

• A. 69
• B. 1812
• C. 1813
• D. 1723

Answer: (C)

RADIUS uses two separate UDP ports to handle different functions: authentication and accounting. For accounting, the standard port is 1813. This means the NAS sends Accounting-Request messages to the RADIUS server on UDP port 1813, and the server replies back to the requester’s address/port. The other options refer to different services, not RADIUS accounting: 69 is the port used by TFTP, 1812 is used for authentication (not accounting) with RADIUS, and 1723 is associated with PPTP VPN traffic. So 1813 is the correct port for RADIUS accounting.

RADIUS uses two separate UDP ports to handle different functions: authentication and accounting. For accounting, the standard port is 1813. This means the NAS sends Accounting-Request messages to the RADIUS server on UDP port 1813, and the server replies back to the requester’s address/port.

The other options refer to different services, not RADIUS accounting: 69 is the port used by TFTP, 1812 is used for authentication (not accounting) with RADIUS, and 1723 is associated with PPTP VPN traffic. So 1813 is the correct port for RADIUS accounting.