Each user account or security group is uniquely identified with a SID (Security ID) and a GUID (Global Unique ID). If a user or group has been deleted, and is then re-created with the same name, the SID and GUID of the newly created user or group will differ from those of the deleted object. As a result, the new user or group loses all permissions, profile settings, and all other settings associated with the old SID and GUID.
When you restore a deleted user or group from a backup, the restored user or group will have the same SID and GUID as the deleted object, and will have all the settings associated with that SID and GUID.
You can restore individual objects using the Online Restore feature of Recovery Manager for Active Directory. Alternatively, you can restore the entire Active Directory database, and then select individual objects for authoritative restore.
While Recovery Manager for Active Directory supports both methods, online restore is the recommended option as it is faster and simpler. The online restore method allows you to easily restore individual directory objects and object attributes without restarting domain controllers and putting Active Directory offline, thus achieving near-zero downtime.
The Recovery Manager for Active Directory online restore method facilitates the restoration of objects and objects attribute values, without putting Active Directory offline. The product can:
In the latter scenario, Active Directory retains the object’s tombstone for a specified configurable period of time (tombstone lifetime) in order to enable Active Directory replication to propagate the deletion. An object can only be undeleted if its tombstone exists. After applying the backed-up attribute values, the online restore process adjusts replication-related properties of the restored objects, so that Active Directory replication propagates the restored data to all domain controllers. Optionally, online restore can force replication of the restored data to decrease propagation delay.
When Microsoft’s Active Directory Recycle Bin feature is enabled in the Active Directory forest, Recovery Manager for Active Directory can use the functionality provided by Microsoft’s Active Directory Recycle Bin feature to undelete the object with all its attributes and links to the state the object was in immediately before deletion. No backups required in this recovery scenario.
In other recovery scenarios, when Microsoft’s Active Directory Recycle Bin feature is disabled or not supported, Recovery Manager for Active Directory first restores all the attributes preserved in the object’s tombstone. The remaining attributes are then restored from backup. If the backed-up value of an attribute differs from the value restored from the tombstone, then the backed-up value is restored. As a result, after the recovery operation completes, the restored object has the same attribute values, group memberships, and security descriptor as it had when the backup was created.
It is possible to determine which attributes are preserved in object tombstones by analyzing the AD schema. In such attributes, the third bit in the searchFlags property is set to 1. You can therefore enumerate these attributes using a filter that contains a matching rule such as the following: