How does RADIUS enhance network security?

RADIUS, which stands for Remote Authentication Dial-In User Service, enhances network security primarily through centralized authentication, authorization, and accounting services. This means that when a user attempts to connect to the network, their credentials are validated against a centralized server rather than on each individual device or access point. This approach not only simplifies user management but also increases security by ensuring that authentication policies are uniformly enforced across the network.

Centralized authentication reduces the risk of unauthorized access because it allows for better monitoring and management of user credentials. Additionally, RADIUS accounts for real-time accounting, which keeps track of users' activities while connected, providing further visibility into user behavior and security.

While the other options touch on important aspects of security, they do not accurately describe the primary role of RADIUS. Encrypting all data transmitted over the network, implementing multi-factor authentication, and segregating network traffic into smaller subnets are valuable security measures but are not the defining features of RADIUS. In fact, RADIUS does not encrypt the entire data transmitted over the network; it primarily encrypts only the passwords during the authentication process, which is a protective measure but not as comprehensive as what the correct answer describes.