How does netdiag work?

Netdiag is a tool used by Windows Administrators and if entered into the environmental variables can be run from the command line as "Netdiag" with its specific switches. Netdiag works by interfacing with specific objects of an operating system these might be COM+ or WIN32 objects to return values such as subnet mask, gateway address' etc...

if you are looking to as how it works as a tool you need to open a command prompt (elevated preferably) and enter in the "netdiag" command (ensuring that it has been added to environmental variables) with specific syntax of a task you are trying to achieve.