System-wide configuration settings and some ASP.NET schema settings are stored in a file named Machine.config, which is located in the
%SystemRoot%\Microsoft .NET\Framework\versionNumber\CONFIG directory.
This directory also contains other default settings for ASP.NET Web applications in a file that is referred to as the root Web.config file. ASP.NET configuration files for individual Web sites and applications, which are also named Web.config files, can be stored in any Web site root directory, application root directory, application subdirectory, or all of these. For more information, see ASP.NET Configuration File Hierarchy.