Mastering Active Directory

Before installing the AD Connect server

Before installing the AD Connect server, we need to check whether the existing environment meets the following requirements. They can be found at https://docs.microsoft.com/en-us/azure/active-directory/connect/active-directory-aadconnect-prerequisites:

• The AD forest functional level must be Windows Server 2003 or later.
• If you plan to use the password writeback feature, then the domain controllers must be on Windows Server 2008 (with the latest SP) or later. If your DCs are on 2008 (pre-R2), then you must also apply hotfix KB2386717.
• The domain controller used by Azure AD must be writable. Using a read-only domain controller (RODC) is not supported, and Azure AD Connect does not follow any write redirects. ...