given an IXMLDOMDocument, or debugging the Common Language Runtime (CLR). These extensions are a large part of what makes WinDbg such a powerful debugger. WinDbg is used by the Microsoft Windows product team to build Windows, and everything needed to debug Windows is included in these extension DLLs. Extension commands are always prefixed with !. While some extensions are used only inside Microsoft, most of them are part of the public Debugging Tools for Windows package. The extension model is documented in the help file included with the Debugging Tools for Windows. Ext.dll Ext is a standard Windows Debugger extension that ships with WinDBG and is loaded by default. !analyze command The most commonly used command is !analyze -v, which analyzes the current state of the program being debugged and the machine/process state at the moment of crash or hang. This command is often able to debug the current problem in a completely automated fashion. When used without any switches, !analyze simply returns the results of its analysis. The -v and -vv give further details about that analysis. Wow6432exts.dll Wow6432exts is a standard Windows Debugger extension that ships with WinDBG. It is used to debug processes running inside WoW64 (32-bit processes running in 64-bit Windows). SOS.dll The SOS (Son of Strike) Debugging Extension (SOS.dll) assists in debugging managed programs in Visual Studio and WinDbg by providing information about the internal common language runtime (CLR) environment. This tool requires a project to have unmanaged debugging enabled. SOS.dll is automatically installed with the .NET Framework. To use SOS.dll in Visual Studio, install the Windows Driver Kit (WDK). To debug a process or memory dump, the sos.dll version must match the .NET Framework version. Psscor2 and Psscor4 are a superset of SOS. Psscor2.dll Psscor2 is the Windows Debugger Extension used to debug .NET Framework applications that use the .NET CLR version 2.0 (.NET Framework versions 2 through 3.5). Psscor2 was developed for internal use at Microsoft as part of their Product Support Services tools. While Microsoft only released Psscor2 in 2010 Microsoft had been publishing commands from the extension several years before, causing difficulty for those who were trying to follow their processes. Psscor4.dll Psscor4 is a Windows Debugger extension used to debug .NET Framework 4 applications. Coupling with virtual machines WinDbg allows debugging a Microsoft Windows kernel running on a virtual machine by VMware, VPC or Parallels using a named pipe. This