Which Azure feature allows for automatic backups of Active Directory?

Azure AD Domain Services is the feature that enables automatic backups for Active Directory. This service provides managed domain services like domain join, group policy, lightweight directory access protocol (LDAP), and Kerberos authentication, without the need for deploying, managing, and patching domain controllers in the cloud.

In the context of Azure AD Domain Services, automatic backups are crucial as they ensure the continuity and recovery of Active Directory data. This feature protects against the loss of directory information caused by accidental deletions or other issues by allowing administrators to restore data from backups when necessary.

The other options are built for different purposes: Azure SQL Database is focused on managing relational database applications with built-in backups for SQL databases but does not apply to Active Directory; Azure Site Recovery is designed for disaster recovery of virtual machines and applications but does not specifically manage directory services; and Azure Blob Storage serves as a storage solution for unstructured data, not for managing or backing up Active Directory.