Troubleshooting Microsoft Entra Pass-through Authentication in Multi-Forest Environments
Microsoft Entra Pass-through Authentication (PTA) allows users to sign in to Microsoft Entra ID using passwords that are validated directly against on-premises Active Directory. In a single Active Directory forest, this password validation path is usually straightforward. In a multi-forest environment, however, the PTA agent may need to validate users located in another forest through an Active Directory forest trust. In this scenario, the PTA agent itself can be healthy and successfully validate users in one forest, while Microsoft Entra sign-ins for users in another forest fail through the same agent. In this article, we will look at how Forest Trust and Name Suffix Routing can affect cross-forest password validation with Microsoft Entra Pass-through Authentication. Scenario The lab contains two Active Directory forests: lab.local lab3.local A two-way forest trust is…