There are a number of different approaches you can use when problem solving and selecting the most effective troubleshooting approach will allow you to resolve a problem in less time as you will be more efficient.
The two sub pages from this page outline two different types of troubleshooting approach (half split and linear, which covers top-down and bottom-up), to make a decision on which one to use you must first;
1. Determine the scope of the problem.
2. Apply your experience.
3. Analyse the symptoms.
The first step, ‘determining the scope of the problem’, means you should select the troubleshooting approach based on the perceived complexity of the problem. A bottom-up approach typically works better for complex problems. A top-down approach is typically best for simpler problems. Using a bottom-up approach for a simple problem might be wasteful and inefficient. If we were to imagine a typical PC Helpdesk that is usually receiving help requests from users, then you should use a top-down approach because it is more likely that the problem will be found quicker that way.
If the symptoms have been reported by equipment on the network such as network monitoring devices, then using a bottom-up approach will likely be more effective.
The second step, ‘applying your experience’ means that if you have previously successfully cured a particular problem in the past (or perhaps a similar problem) Then you might know of a way or a shortcut to expedite the troubleshooting process. If you are less experienced, you likely will implement a top-down approach regardless of the circumstances.
In contrast, if you are skilled at troubleshooting, you might be able to get a head start by beginning at a different layer using the Half-Split method.
Analyzing the symptoms allows you to have a better chance of solving a problem if you know more about it. At times, you can immediately correct a problem simply by analyzing the symptoms and swiftly recognizing the culprit.
To give an example, if you received a call from an individual in a department who is complaining that they cannot print. You would first find out if others in the department could print, then ask if the individual could print whilst logged into another departmental machine. If the other members can print and the staff member can print from another machine, then you must suspect the staff members own machine and employ a top-down approach whilst at that machine.