Non-Published Office 365 Directory Sync with Azure ExpressRoute

In one of my recent sessions with a customer, the customer expressed an interest in protecting their communication between Office 365 and their on-premise environment for the purposes of making their directory synchronization server traffic invisible to the outside world. This got me thinking about Azure ExpressRoute which we know can provide very fast connectivity between your on-premise environments and Azure if you are using a supported MPLS network provider.

The customer in question is using Level 3 Networks as their carrier and Level 3 are on the supported carriers list for ExpressRoute on the ExpressRoute Technical Overview page at so I looked into it a little bit further as this was a really interesting proposition – to have Office 365 SaaS managed productivity with Exchange, SharePoint and Lync but to have all of the sync traffic traffic privately routed over ExpressRoute so that you weren’t passing any of that data over the public network (albeit encrypted with HTTPS SSL).

When I looked further, I found that on the ExpressRoute FAQ page at it explicitly defines which Azure services are accessible over an ExpressRoute connection and Azure Active Directory (AAD) is not listed nor is anything in relation to Office 365.

Unfortunately, it seems that this isn’t possible right now but it would be nice to see something added in the future to allow AAD to be access over ExpressRoute to allow us to hide and conceal our ADFS or AADSync traffic as this may well answer a security question that some more conscious customers have. The other reason this would be nice as it means we can have our internal users accessing their mail and SharePoint via the ExpressRoute connection so they will get a faster experience that over the companies internet link. Right now however, the best use case for ExpressRoute in my opnion is Azure RemoteApp, allowing you move some or all of the Remote Desktop Services terminal server farms that you may have to Azure and offload your RemoteApp applications to the cloud.


Richard works as a Cloud Consultant for Fordway Solution where his primary focus is to help customers understand, adopt and develop with Microsoft Azure, Office 365 and System Center. Richard Green is an IT Pro with over 15 years' of experience in all things Microsoft including System Center and Office 365. He has previously worked as a System Center consultant and as an internal solutions architect across many verticals. Outside of work, he loves motorbikes and is part of the orange army, marshaling for NGRRC, British Superbikes and MotoGP. He is also an Assistant Cub Scout Leader.