Microsoft Azure Active Directory (AD) Connect is the best way to connect your on-premises directory with Azure AD and Office 365. Now great time to upgrade to Azure AD Connect from Windows.
The two identity synchronization tools that are deprecated were offered for single forest customers (DirSync) and for multi-forest and other advanced customers (Azure AD Sync). They will reach end of support on April 13, 2017.
These older tools have been replaced with a single solution that is available for all scenarios: Azure AD Connect. It offers new functionality, feature enhancements, and support for new scenarios. To be able to continue to synchronize your on-premises identity data to Azure AD and Office 365, we strongly recommend that you upgrade to Azure AD Connect.
For more information about this transition, please visit the Azure AD Connect webpage.