Which authentication method is commonly associated with LDAP directory lookups?

The authentication method commonly associated with LDAP (Lightweight Directory Access Protocol) directory lookups is Kerberos. Kerberos is a network authentication protocol designed to provide secure authentication for clients and services through the use of tickets. It operates in conjunction with directory services like LDAP to validate user credentials, making it a strong choice for environments where LDAP serves as the directory backend.

While SAML (Security Assertion Markup Language) is often used for single-sign-on (SSO) and federated identity management, it functions differently by exchanging authentication and authorization data between identity providers and service providers. OAuth is primarily an authorization framework rather than an authentication protocol, allowing limited access to resources without exposing user credentials. RADIUS (Remote Authentication Dial-In User Service) is also an authentication, authorization, and accounting protocol but is more associated with network access control.

In summary, Kerberos is the correct answer because of its role in providing secure authentication in environments that utilize LDAP for directory services, ensuring that user identities are validated properly through a ticket-based system.