The IIS session timeout value is for classic pages only .asp. For ASP.NET applications, only the specified timeout value in web.config is applied. This means that the settings for the Web.Config session will override the IIS settings for .aspx pages.
Secondly, in ASP.NET/Framework 2.0 you get the ASP.NET tab in IIS, where you can control the configuration file settings. This affects ASP.NET, but not classic ASP applications.
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