What is the primary role of RADIUS in EAP deployments?

• A. An EAP method
• B. A transport protocol that carries EAP messages to the authentication server
• C. A wireless security protocol
• D. A VPN protocol

Answer: (B)

RADIUS in EAP deployments serves as the transport that carries EAP messages from the network access server to the authentication server. EAP defines how credentials are exchanged, but it relies on a transport to move those messages. The EAP method (such as EAP-TLS or PEAP) runs between the client and the authentication server, while RADIUS packages the EAP payload into its Access-Request messages and forwards them over UDP to the RADIUS server. The server then responds with Access-Accept, Access-Reject, or Access-Challenge, and the NAS relays that back to the client. Because of this role, RADIUS is not an EAP method, nor a wireless security protocol, nor a VPN protocol.