Who forwards EAP messages between the supplicant and the authentication server in 802.1X?

• A. Supplicant
• B. Authenticator
• C. Central authentication server
• D. All participants

Answer: (B)

In 802.1X, the authenticator acts as the mediator between the user device (the supplicant) and the authentication backend. The supplicant sends EAPOL frames to the access device (switch or AP), and the authenticator forwards these EAP messages to the authentication server (often a RADIUS server) for verification. The server responds back through the authenticator, which then conveys the result to the supplicant and enforces port access accordingly. The central authentication server doesn’t directly talk to the supplicant on the access port, and the supplicant doesn’t forward messages to the server itself. So the entity that forwards EAP messages between the supplicant and the authentication server is the authenticator.