Final answer:
RADIUS provides two elements of the AAA security model: Authentication, verifying who a user is, and Accounting, tracking what a user does. It does not inherently provide Authorization, which determines what a user can do.
Step-by-step explanation:
The AAA model in network security stands for Authentication, Authorization, and Accounting. RADIUS (Remote Authentication Dial-In User Service) is a networking protocol that provides two of the three A's: Authentication and Accounting. This means RADIUS is designed to manage a user's access to a network and keep track of their activities while they are logged on. However, RADIUS does not inherently provide detailed Authorization capabilities; this function is often handled by other systems or extensions to the RADIUS protocol.