Last week I faced a strange issue recently, i have deployed SharePoint 2003 servers for one project and one of the requirements was to open SharePoint site from same server. when i was trying to open site from the same server i was getting authentication prompts and the site was not opening. I have even added the URL entry in the local host file but the issue remains same. After googling i found one Microsoft KB on the same issue which stated that “This issue occurs if you install Microsoft Windows XP Service Pack 2 (SP2) or Microsoft Windows Server 2003 Service Pack 1 (SP1). Windows XP SP2 and Windows Server 2003 SP1 include a loopback check security feature that is designed to help prevent reflection attacks on your computer. Therefore, authentication fails if the FQDN or the custom host header that you use does not match the local computer name.”
In order to fix this we need to disable loopback check on all web servers which are facing this behavior. I have applied this fix on my both front-end servers and after restarting both front-end servers i have checked and the issue was resolved . I can now open my portal website on same front-end servers. Following is the fix i followed.
Method 1: Disable the loopback check
•Click Start, click Run, type regedit, and then click OK.
•In Registry Editor, locate and then click the following registry key:
•Right-click Lsa, point to New, and then click DWORD Value.
•Type DisableLoopbackCheck, and then press ENTER.
•Right-click DisableLoopbackCheck, and then click Modify.
•In the Value data box, type 1, and then click OK.
•Quit Registry Editor, and then restart your computer