Which protocol uses SSL/TLS to secure directory access services?

The correct answer is LDAPS, which stands for Lightweight Directory Access Protocol over SSL/TLS. This protocol is specifically designed to secure communications between clients and directory services such as Active Directory or LDAP servers. By leveraging SSL (Secure Sockets Layer) or its successor TLS (Transport Layer Security), LDAPS encrypts the data exchanged during directory operations, which is essential for safeguarding sensitive information like user credentials and directory data from eavesdropping or tampering.

The importance of using LDAPS comes from the need to protect directory access services in environments where sensitive information is transmitted. When utilizing LDAPS, organizations can ensure that the connections to their directory services are secure, thus reinforcing the overall security posture of their identity management and authentication processes.

In contrast, other protocols such as OAuth, RADIUS, and Diameter serve different purposes within the realm of network security and access control. OAuth is primarily an authorization framework rather than a protocol for securing communications, while RADIUS (Remote Authentication Dial In User Service) and Diameter are used for authentication, authorization, and accounting, but they do not natively include SSL/TLS for securing directory access services. Hence, LDAPS stands out as the appropriate choice for securing LDAP communications specifically through encryption.