What is a valid reason for using session based authentication instead of IP based authentication in a FortiGate web proxy solution?

Session-based authentication, when properly implemented with cookies or other mechanisms, typically aims to reduce the frequency of credential re-entry, making this statement an incorrect reason for its preference.

FSSO (Fortinet Single Sign-On) is an authentication method that can integrate with various user identification strategies, but it doesn't solely necessitate session-based authentication over IP-based as a primary reason.

When multiple users originate from the same IP address (e.g., behind a NAT device or on a terminal server), IP-based authentication cannot differentiate between them, whereas session-based authentication can uniquely identify and manage each user's web session.

RADIUS is an authentication protocol used to verify user credentials; it defines *how* authentication is performed, not *why* one would choose session-based over IP-based identification for proxy traffic.