When troubleshooting any problem, ask yourself the following questions:
What application is failing? What works? What doesn't work?
Is the problem basic IP connectivity or is it name resolution? If the problem is name resolution, does the failing application use NetBIOS names or DNS names and host names?
How are the things that do and don't work related?
Have the things that don't work ever worked on this computer or network?
If so, what has changed since they last worked?
Ideally, a review of the location and timing of the problem helps narrow the problem's scope. In addition, you can examine TCP/IP failures systematically by referring to the steps needed for successful computer communications . These steps are described in the following sections; suggested methods for troubleshooting begin in the "Unable to Resolve a Host or NetBIOS Name" section of this chapter.