What authentication type is the default for active directory?

The correct answer is that Kerberos is the default authentication type for Active Directory. Kerberos is a network authentication protocol that uses secret-key cryptography to provide secure authentication over a non-secure network. It is designed to eliminate the need for transmitting passwords across the network, instead issuing tickets that allow users to prove their identity securely and obtain access to resources.

The preference for Kerberos over NTLM, which is indeed a legacy authentication protocol still supported in Active Directory for backward compatibility, is due to Kerberos's more secure and efficient architecture. Kerberos mitigates various attacks that could compromise user credentials and ensures that both authentication and communication are handled securely.

LDAP, or Lightweight Directory Access Protocol, is primarily used for querying and modifying directory services but does not handle authentication directly in the same way as Kerberos or NTLM. SAM refers to the Security Account Manager, which is a database used by Windows to store user accounts and passwords, but it is not an authentication mechanism employed by Active Directory for user sign-ins.

Understanding that Kerberos is the default protocol in Active Directory can help clarify its role in maintaining security and efficient access control within Windows network environments.