I\'m doing research for an article on the ASP.NET Pipeline, but none of the resources I\'ve covered so far adequately explain when the machine level, and application level,
ASP.NET config files work in a hierarchical manner (much the same way as CSS elements).
Configuration Inheritance
The most comprehensive description of how asp.net configration files work that I know of is this one at MSDN:
ASP.NET Configuration File Hierarchy and Inheritance
It is written for the .NET 3.5 framework so the info should be as current as you'll likely find. It describes exactly how the various configuration files are read and merged into the runtime settings for the application in quite a lot of detail.