CompTIA Network+ Practice Test 2026 - Free Network+ Practice Questions and Exam Prep Guide

RADIUS, which stands for Remote Authentication Dial-In User Service, is specifically designed for centralized authentication, authorization, and accounting for users who connect and use a network service. It operates as a client-server protocol and enables the enforcement of security policies across a network by authenticating users before granting access. This is particularly useful in Wi-Fi networks, VPNs, and other environments where user identification and secure access is critical.

The other protocols serve different purposes that do not relate to centralized authentication. TCP/IP is the suite of protocols that governs how data is transmitted over a network but does not perform any authentication functions. DHCP, or Dynamic Host Configuration Protocol, automatically assigns IP addresses to devices on a network but also lacks authentication capabilities. FTP, or File Transfer Protocol, is used for transferring files between systems, but does not provide any centralized authentication features. Therefore, RADIUS stands out as the correct choice for centralized authentication in network security.