Microsoft Support Diagnostic Tool or MSDT is a tool in Windows 7 and Windows Server 2008 R2, which is used by Microsoft Support to help diagnose Windows problems.
When you contact Microsoft Support for any help, the support professional will give you a Passkey.
You are required to open the Microsoft Support Diagnostic Tool and enter the Passkey.
To do so, type msdt in Start Search box and hit Enter. Once you have have entered the passkey, the Tool will be activated and you have to only follow the wizard.
You may also be provided with an Incident Number to enter into the tool to identify your information. The tool may require you to download additional diagnostic tools and answer some questions. Once the tool runs its course, it will save the results. You can then send the results to Microsoft.
Microsoft Support uses the information that Microsoft Support Diagnostic Tool (MSDT) collects to analyze and then determine the correct resolution to problems that you are experiencing on the computer. The information may also be used to automatically perform common troubleshooting tasks.
You can also run MSDT if you do not have an internet connection.
This can be done so, through a package that is generated on a computer that has an Internet connection. This package is called Offline package. This Offline package will execute on the destination computer, generate a CAB file with diagnostic information which can then be sent to Microsoft support.
To know more about Microsoft Support Diagnostic Tool visit KB973559.