What authentication method must be used when Windows authentication is not allowed?

The correct answer involves using web ticketing alongside LDAP credential verification, which is essential when Windows authentication is not permitted. This method ensures secure access for users by leveraging web tickets, which are temporary credentials granted to authenticated users. These tickets verify their identity during the session, while LDAP (Lightweight Directory Access Protocol) facilitates the retrieval of user credentials from a central directory.

By combining these two approaches, organizations can maintain secure access control without relying on Windows-based authentication, which might not be feasible in all scenarios. This method is particularly useful in environments where users need to authenticate across multiple platforms or where integration with other systems is required.

Other methods, such as basic username and password systems, token-based authentication, or direct VPN access, might not provide the same level of security or flexibility as the combination of web ticketing with LDAP, making them less suitable in environments sensitive to security and scalability concerns.