I have a multi-site Windows Server 2012 R2 AD domain.

Up until now we have been using individual office licenses.

At one specific site, we are testing an Office 365 implementation.

  1. How do I integrate the Office 365 accounts into the on premise AD structure so that users don't have to memorize another set of credentials for Office 365?

  2. I've run across some guides that seem to explain how to do this, but all involve setting up stuff on the Domain Controller. What is not clear to me is:

    How do I set up this integration only for the site where we are doing the rollout? It only applies to that site and specific users at that site.

    Which DC do I setup the integration at? The main DC (off-site) for the entire organization? The local DC at the site where we are rolling out Office 365? If I have two DCs on site (as is best practices), do I setup integration on both DCs?

    This is another part that seems nebulous to me: we have one AD across several (international) sites, but each local office will purchase and maintain their own Office 365 accounts (here I'm talking about organizational accounts not user accounts) for their own local users for accounting and licensing reasons. Is it possible to integrate multiple organizational Office 365 into a single AD? How do you set it up so that the AD / Office 365 integration knows where to find the Office 365 account?

  1. You install Azure AD Connect on a server in your on-premises environment and connect it to your Office 365 tenant. Users, groups and passwords are synchronised to the cloud, creating a mirrored AD in cloud (same sign on). *An alternative option is to use ADFS to federate with Office 365 - single sign on.

  2. You can install Azure AD Connect on any server that fits the requirements, it doesn't have to be a DC. When configuring AADC you can choose which OUs to synchronise.

Synchronising one AD to multiple Office 365 accounts (called 'tenants') is trickier but supported (with limitations). See the section in this document titled 'Each object only once in an Azure AD tenant'. Basically you install one AADC server for each tenant and configure OU filtering to synchronise the required objects from AD to each office 365 tenant.

In this topology, one Azure AD Connect sync server is connected to each Azure AD tenant. The Azure AD Connect sync servers must be configured for filtering so that each has a mutually exclusive set of objects to operate on. You can, for example, scope each server to a particular domain or organizational unit.1

A DNS domain can be registered in only a single Azure AD tenant. The UPNs of the users in the on-premises Active Directory instance must also use separate namespaces.

  • It looks like having multiple tenants needlessly complicates the situation. How does Microsoft view this, then, when you have an international company with licensing that covers several different regions? Do they just not care when it comes to Office 365?
    – Daniel
    Mar 10 '17 at 17:32
  • There's brief discussion at the link below, but I'd advise speaking to MS directly. They don't bite! blogs.technet.microsoft.com/uspartner_ts2team/2015/06/01/… Mar 13 '17 at 10:36

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