Which EAP method uses a protected access credential to establish mutual authentication between devices?

• A. EAP-FAST
• B. EAP-TLS
• C. EAP-MD5
• D. EAP-TTLS

Answer: (A)

Mutual authentication in EAP methods can be bootstrapped in different ways. The method that uses a Protected Access Credential is EAP-FAST. PAC is a credential shared between the client and the authentication server that helps establish a secure, trusted channel without needing full certificate management. Once the PAC is used to bootstrap this protected tunnel, both ends can verify each other and derive keys, enabling mutual authentication within the secured tunnel.

Other options rely on certificates or simple password mechanisms. EAP-TLS and EAP-TTLS depend on certificates to achieve server and client trust, which is different from using a PAC. EAP-MD5 uses a basic password hash and does not provide strong mutual authentication.