Over the past few weeks I have run into and been asked about SharePoint prompting for credentials a bunch of times. There are a number of different reasons this could happen. Most commonly it is because the SharePoint site isn’t in the Trusted Sites or Local Intranet IE security zones. If it is in the Internet zone by default the browser doesn’t pass your credentials along which is a good thing that we don’t what to change. Assuming that your site is in Trusted Sites or the Local Intranet zone then the next thing to check would be whether or not Integrated Windows Authentication is enabled. To do this in IE you click tools, internet options, then the advanced tab and under the security section make sure the checkbox is checked.
If you are still getting prompted at this point. The last setting that seems to do the trick every time is another IE security setting. Go back into Tools –> Internet Options and then the security tab. Once in there click on the zone your site is in, for this example its local intranet. Then click the custom level button and all the way at the bottom of the window that opens up under the User Authentication section make sure that Automatic Logon with current user name and password is selected. Click OK restart the browser and enjoy the no more prompts.
If you have any questions or other suggestions please feel free to leave a comment.