Active Directory
Veeam supports Application Aware backup of Active Directory for Virtual Machine and Physical Servers.
Preparation
For Microsoft Active Directory, check the tombstone lifetime settings, as described in Veeam Explorers User Guide at Veeam Help Center When possible, it’s recommended to backup the Domain Controller with most FSMO
You can run netdom query fsmo to check with Domain Controller have which FSMO roles.
Job configuration
For backup and restore of domain controllers to work properly application aware image processing option has to be enabled in the job properties.
References
Helpcenter - Tombstone Lifetime Settings