When it comes to debugging, symbol files are essential. Whenever you build an application in VS, build system normally generates symbols files (.pdb files) togather regardless of Release or Debug build configuration. So you have symbols files for your own application. But then how can get symbol files for OS. For Windows OS, Microsoft provides public symbol server.
To set the symbol server on your debuggeer, simply set the following symbol server path:
For example in WinDbg,
(1) You can set it in command mode:
(2) Or set the symbol path in File menu. Select File-> Symbol File Path... and type the path as follows: