How does the OS distinguish between executable types

Question

Executable files created through managed framework like .Net have .exe extension whereas application created through languages like C++ also has .exe extension. How does the OS knows whether to run the application through managed framework like .Net or directly ?

Answer 1

The COM Descriptor Data Directory (DD 14) is used to lookup the COR20 structure. This is how you can tell the difference between a managed executable and a native executable.

See this question for more information. Also see this introduction to the dotnet file format for an overview.