Recently I was switching Office 365 tenant from ADFS to Azure AD Pass-through authentication (PTA). It all went smoothly with one exception. After removing one of the Azure AD Connect servers and all applications from its Azure AD Connect interface still is showing said agent, just inactive.
azure adconnect
Azure AD Connect allows three ways to make sure the user password is the same in Active Directory and Office 365. Those are Password Hash Sync, Pass-Thru Authentication, and ADFS. While my preferred option to go with would be Pass-Thru Authentication, only Password Hash Synchronization is the easiest and least resource-intensive. It synchronizes user password to Office 365, and even if your Active Directory is down, you can still log in to Office 365. It’s perfect for small and even more significant companies that don’t have resources or can’t guarantee that their infrastructure will stay 100% time online so users can authenticate based on their Active Directory.
