Avoiding 401 response for each request using NTLM

Question

We have here an asp.net 3.5 application using NTLM based windows authentication. The system runs on a private network that actually distributed over different geographic pla

Answer 1

I have the exact same problem! I am using the same environment as you. Except that I see 2 401's even in Fiddler. I had spent a couple of days on that problem and then just gave up on it. AuthPersistence did not work for me either. But here are the links that I had found, maybe they will work in your case.

http://msdn.microsoft.com/en-us/library/ms525244.aspx

http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/b0b4ec5c-74f8-43e9-ac64-d8b852568341.mspx?mfr=true

http://technet.microsoft.com/en-us/library/cc786094.aspx

http://technet.microsoft.com/en-us/library/cc781339(WS.10).aspx

I tried to set the flag at both the virtual directory and website level, but it didn't help. Are you using the IIS Metabase Explorer to edit those properties? Its the cleaner way to edit properties and may help more than directly editing the XML file.

One way to circumvent the problem is to insert the Cache-Control Header in the HTTP response for the resources that are not going to change frequently on any page. In my case, I cached the css (use external css as much as possible to optimize this), js and img files. Since I have about 60 files of these types that get loaded on our homepage, we were able to eliminate about 120 401 errors straight away!

Make sure you use the Cache-Control header and not the if-modified or e-tag based caching where a 401 and a 304 will still be generated even when the files are cached.