According to the Microsoft Identity and Access Administrator (SC-300) Study Guide and Microsoft Learn documentation on “Enable Microsoft Entra login for Windows Server and Windows virtual machines in Azure”, successful sign-in to Azure VMs using Microsoft Entra (formerly Azure AD) credentials requires network connectivity to specific Microsoft identity endpoints. One of the most critical endpoints is https://enterpriseregistration.windows.net , which is used during the device registration and Microsoft Entra Join process.

When you enable Microsoft Entra login for Azure VMs, each VM must register itself as a device in the directory to allow authentication using Entra credentials. If the VM cannot reach the enterprise registration service, the registration fails, meaning the VM will not appear as a valid device in Entra ID. Consequently, users attempting to log in with their Entra credentials will encounter sign-in errors because the system cannot validate their device trust and user token against the identity service.

Microsoft documentation explicitly states:

“To enable Microsoft Entra sign-in to Windows VMs in Azure, the VM must be able to communicate with Microsoft Entra endpoints, including https://enterpriseregistration.windows.net , to complete device registration.”

Options B, C, and D are unrelated to initial configuration issues. Revoking refresh tokens or deleting device registrations would not resolve connectivity or registration failures. SSH support (option D) is applicable to Linux VMs, not Windows.