DirSync & Azure AD Sync refused by Azure AD per December 31st. Upgrade to Azure AD Connect NOW!
Azure AD Connect is the best way to connect your on-premises directory with Azure AD and Office 365. The time to upgrade to Azure AD Connect from Windows Azure Active Directory Sync (DirSync) or Azure AD Sync has come! As these tools are now deprecated and will reach end of life on December 31, 2017.
You can configure Azure Active Directory Domain Services (Azure AD DS) by using the new Azure portal (portal.azure.com). This feature is now GA (generally available) in all Azure regions that the service supports.
All existing managed domains have been migrated to the new portal from the Azure classic portal. You can configure and manage existing managed domains by using the new Azure portal.
To get started, see the documentation.