Microsoft Azure can be used as a secondary location to keep a copy of Active Directory. If a disaster hits the primary site that makes Active Directory partly or totally unavailable, you have at least Active Directory still operational in a secondary location.

Think about how much time this saves compared to having to fully restore one of your most crucial assets. You can have an Active Directory server in Microsoft Azure as a replica. In this section, I will describe the steps you need to take to create such a replica.

The requirements include a VPN connection between your on-premises infrastructure and the Microsoft Azure network. For security reasons, it is not advised to have Active Directory replication over the public interface of Microsoft Azure using endpoints.

This webpage provides step-by-step instructions on how to configure AD replication to Azure: http://blogs.technet.com/b/keithmayer/archive/2013/01/20/step-by-step-extending...