Watch this video to learn about the new option of authentication in Azure Active Directory Connect tool: Pass-through authentication
Pass-through authentication provided by Azure Active Directory enables users to login to cloud resources by validating their password against their on-premises local Active Directory.
This feature allows customers that cannot or don't want to store passwords in the cloud to onboard Azure Active Directory and Office 365 without having to modify their corporate network infrastructure and install products such as ADFS or similar 3rd party federation solutions.
Pass-through authentication is available via Azure AD Connect as the 3rd option of authentication along with Password Sync and ADFS.
Additionally, with this new update, both "Pass-through authentication" and "Password Sync" authentication options will provide seamless single sign-on to Azure AD connected applications from Windows devices, as ADFS was offering until now.