IIS7 UNC File caching issue

You have to either choose dir-monitoring and file-change-notification with its drawback of using SMB resources or periodic file attribute check with its drawback of serving stale content for a period of time.

If you can write a native module, you can use IHttpServer::NotifyFileChange to notify the file-cache of the file changing when you manually change it.

http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/49fb1790-3a4b-41e3-85a0-3fcfd76b8cb6.mspx?mfr=true

http://blogs.iis.net/ksingla/archive/2007/12/30/list-of-registry-keys-affecting-iis7-behavior.aspx