Directory Synchronization
Directory Synchronization allows organizations with an Active Directory (AD) environment to synchronize AD users and groups to an Azure Active Directory, which is the identity solution supported by your Office 365 subscription and other Microsoft cloud platforms. The Directory Synchronization tool provided by Microsoft is called Azure AD Connect (AAD Connect) and synchronizes your local active directory into your Office 365 tenant. If you are currently using depreciated tools such as DirSync and AAD Sync, they must be uninstalled before installing the new AAD Connect.
Once you deploy AAD Connect in your environment, you should consider this server to be a permanent addition to your environment. Azure AD Connect can be installed and managed from an existing domain controller in your environment, but must be installed on a Windows Server 2008 or later with the latest service packs and updates installed. It's worth noting that AAD Connect supports not only single forest...
