Which of the following is a function of RADIUS?

RADIUS, which stands for Remote Authentication Dial-In User Service, is primarily designed for centralized management of user accounts and authentication. This function allows organizations to manage user credentials and enforce policies effectively, providing a single point of control for user access to network resources.

By utilizing RADIUS, administrators can authenticate users who are trying to access a network, ensuring that only authorized individuals are granted access. This centralized approach simplifies user management, as any changes to user credentials or access rights can be made in one location, impacting all services that rely on RADIUS for authentication.

The other functions mentioned, such as data encryption, network monitoring, and firewall protection, are not core features of RADIUS. While RADIUS does support secure transmission of credentials through encryption methods during the authentication process, its main goal is not data encryption. Similarly, network monitoring and firewall protection perform different roles in network security management and are not directly related to the primary function of RADIUS. Thus, the centralization of user account management is the key aspect of RADIUS that stands out in this context.