For an ASP.NET MVC 2 application, we are using HttpContext.User.Identity.Name to get the user name for authentication purposes. This works fine when testing. Users who are in the database are able to access areas for which they have permissons, and redirected to a 401 page otherwise. The 401 page displays their username, explaining that this user is not authorized to access this content.
However, in a deployed environment, all attempts to access any portion of the application redirect to the 401 page, and the displayed username is blank!
How can we enable the deployed application to access the username of the request?
From my research, I should go to the following screen and enable Windows Authentication, but it’s not in the list!

Ah, if you are using IIS 7, you probably need to install it first! Here’s a good overview. FTA:
If you’re not seeing it as an option, you probably don’t have it installed.
(Dictated from my Winodws 7 machine,) Go to your Start menu and type: Turn Windows features on or off.
Next, in the dialog’s treeview, go to Internet Information Services – World Wide Web Services – Security and then check the Windows Authentication checkbox.