Now you know how to set up a basic AD synchronization without considering availability infrastructure, and now we'll look at how you can achieve Azure AD synchronization in a high availability environment.
The first thing you should know is that the Azure AD Connect tool cannot be clustered, so you need to use the staged mode to implement it in passive mode.
So, for placement in either high availability or non-high availability infrastructures, it is recommended that you place the systems which are involved in the synchronization in Azure virtual machines. This is so that you do not transfer as much data through the open Internet. More details about these concept will be explained in the next chapter about Azure networking.
In our high availability scenario, every active and primary source of synchronization is placed into Azure. The backup and passive parts are based into the on-premises data center and connected via VPN or MPLS to Azure.
So, to...