Which Azure service is designed for integrating on-premises identity infrastructures with Azure Active Directory?

Azure AD Connect is specifically designed to integrate on-premises identity infrastructures with Azure Active Directory. This service enables organizations to synchronize their on-prem Active Directory with Azure AD, allowing for a unified identity across cloud and on-premises environments. It streamlines the user experience by allowing users to utilize a single set of credentials for accessing resources both within the organization and in the cloud.

This integration is crucial for organizations that want to take advantage of cloud-based services while maintaining their existing on-premises authentication and identity management processes. By syncing identities, Azure AD Connect ensures that any changes made in the on-premises directory, such as user account updates or password changes, are reflected in Azure AD, thereby maintaining consistency and security.

The other options serve different purposes. Azure Active Directory Domain Services provides managed domain services such as domain join, group policy, and LDAP, but does not primarily focus on integration with on-premises directories. Azure Virtual Network is a service for establishing private virtual networks in Azure, allowing for resource communication but not specifically related to identity integration. Azure Lighthouse offers service providers a way to manage customer subscriptions at scale but does not pertain to identity infrastructure.