Suspected loss of session state in IIS 6

I have an ASP.NET web site that responds with multiple skins depending on the domain that it is accessed via.

The problem is that authentication and some other features seem to suffer random glitches where the user is sent back to the log in screen, or other session controlled values appear to have been lost - but only when accessed via one of the domains. The other domain does not suffer the same issue.

On our test system, the issues DOES NOT exist when accessing via any domain. On live, the issue will happen at varying times during the session, even with iden开发者_开发问答tical steps followed. It is for these reasons that I don't think it is a bug in the application software.

On the live system, where the issue is, two websites are set up in IIS, each with bindings to the required domain. One accesses the site through a virtual directory at http://mysite.com/myvirtualdir, the other accesses the site at the root path at http://myalternatesite.com/. I don't think that the virtual directory is the issue however.

I've now solved my problem, though still not sure what the exact cause was.

I opened up website properties for the two websites in IIS, the one that worked and the one that didn't and compared properties.

For anyone else trouble shooting this issue, these are the steps that I took, in order of how likely I think they were to be the cause of the issue.

1. Second website was using Default app pool. There is nothing particular about the Default app pool settings on this server that would cause session to be lost from what I can see, but I have now changed to use the same app pool as the site that was working all along.

2. Disabled windows authentication to match the working website.

3. Changed default documents so that only the required document was listed.

4. Limited connections to 500 to match the working website.

Hope this is of use to somebody else.