Most readers are likely familiar with Azure AD Connect, previously DirSync, Microsoft’s tool for synchronizing Active Directory (AD) accounts to Azure AD. Azure AD Connect can synchronize password hashes to the cloud, which is Microsoft’s recommended option, or alternatively use pass-through authentication (PTA). PTA keeps passwords on-premises and lets organizations enforce Windows Server AD security and password policies.
You can find out more about setting up PTA in Azure AD Connect on Petri here.
After an acquisition, it’s common that IT is required to synchronize identities from a new business group, which has its own AD domains and forests, to the cloud. But Azure AD Connect can’t synchronize identities from disconnected AD forests because it only works with one Azure AD tenant. And Azure AD Connect must be able to connect to every AD forest.
Microsoft added ‘cloud provisioning’ to Azure AD Connect in 2019. Cloud provisioning simplifies synchronizing on-premises identities to Azure AD during mergers and acquisitions. Azure AD cloud provisioning is in preview, so it shouldn’t be used in production environments.
Azure AD cloud provisioning moves the workload from Windows Server AD to Azure AD. It uses lightweight on-premises agents to synchronize accounts from disconnected AD forests to Azure AD. All the synchronization configuration and processing happen in the cloud. High availability is also an option using multiple agents.
But in its current form, cloud provisioning has some limitations. For example, it doesn’t support synchronizing device objects, customer defined AD attributes, pass-through authentication, or attribute value filters. Because of these restrictions, organizations using hybrid Azure AD join or hybrid Exchange deployments will run into problems with cloud provisioning.
For a full list of the limitations, see Microsoft’s website here.
Duplicate objects can pose an issue if the same user exists in AD forests being synchronized to Azure AD. Cloud provisioning doesn’t match objects across disconnected forests, so you’ll need to make sure the objects being synchronized are unique. Duplicate users synchronized using cloud provisioning can result in errors in Azure AD.
Cloud provisioning doesn’t support Exchange hybrid deployments. Microsoft says: “The Exchange Hybrid Deployment feature allows for the co-existence of Exchange mailboxes both on-premises and in Office 365. Azure AD Connect is synchronizing a specific set of attributes from Azure AD back into your on-premises directory. The cloud provisioning agent currently does not synchronize these attributes back into your on-premises directory and thus it is not supported as a replacement for Azure AD Connect.”
It’s not clear when cloud provisioning will hit general availability. Or if the shortcomings I mentioned above, will be addressed in the shipping version. Microsoft updated its FAQ on cloud provisioning in June 2020 but with no changes to the information about hybrid Exchange deployments.
Azure AD cloud provisioning will help synchronize identities to the cloud from disconnected AD forests for some organizations. But if Microsoft isn’t able to address the current limitations, many businesses will need to turn to third-party alternatives.