User1771714573 posted
Hi aholt.hyde,
When a Web browser such as Microsoft Internet Explorer attempts to connect to an IIS server configured for Windows NT Challenge/Response Authentication, the IIS server challenges the browser to perform a complex mathematical calculation on the password
of the logged-on user who is using the browser and to return the result of this calculation to the server.
The server also performs the calculation on the user’s password obtained from a domain controller’s Security Account Manager (SAM) database. If the two calculations agree, the client is considered authenticated. If they differ, the user
is prompted for a valid Windows NT username and password.
If the user provides invalid credentials, the server sends a Hypertext Transfer Protocol (HTTP) status code to the client browser indicating that access is denied unless some other authentication scheme is enabled.
So after enabling windows authentication in IIS, it is very important for non-domain account users to provide account passwords.
Best regards,
Brucz