Deploy Azure AD Pass-through Authentication
Step 1: Check the prerequisites
Ensure that the following prerequisites are in place.
In the Entra admin center
1. Create a cloud-only Hybrid Identity Administrator account or a Hybrid Identity administrator account on your Azure AD tenant. This way, you can manage the configuration of your tenant should your on-premises services fail or become unavailable.
(E) 2. Add one or more custom domain names to your Azure AD tenant. Your users can sign in with one of these domain names.
(A) In your on-premises environment
1. Identify a server running Windows Server 2016 or later to run Azure AD Connect. If not enabled already, enable TLS 1.2 on the server. Add the server to the same Active Directory forest as the users whose passwords you need to validate. It should be noted that installation of Pass-Through Authentication agent on Windows Server Core versions is not supported.
2. Install the latest version of Azure AD Connect on the server identified in the preceding step. If you already have Azure AD Connect running, ensure that the version is supported.
3. Identify one or more additional servers (running Windows Server 2016 or later, with TLS 1.2 enabled) where you can run standalone Authentication Agents. These additional servers are needed to ensure the high availability of requests to sign in. Add the servers to the same Active Directory forest as the users whose passwords you need to validate.
4. Etc.
(B) Step 2: Enable the feature
Enable Pass-through Authentication through Azure AD Connect.
If you're installing Azure AD Connect for the first time, choose the custom installation path. At the User sign- in page, choose Pass-through Authentication as the Sign On method. On successful completion, a Pass- through Authentication Agent is installed on the same server as Azure AD Connect. In addition, the Pass- through Authentication feature is enabled on your tenant.
Incorrect:
Not C: From Active Directory Domains and Trusts, add a UPN suffix
Not D. Modify the email address attribute for each user account.
Not F. Modify the User logon name for each user account.
Reference:
https://learn.microsoft.com/en-us/azure/active-directory/hybrid/connect/how-to-connect-pta-quick-start