Network Troubleshooting Methodology | CompTIA Network+ N10-007 | 5.1

In this video you will learn how to identify a problem; establish a theory of probable cause; test the theory to determine the cause; establish a plan of action to resolve the problem & identify potential effects; implement the solution or escalate as necessary; verify full system functionality, and if applicable, implement preventative measures; and finally, document your findings/lessons learned, actions, and outcomes.

Troubleshooting Methodology

Identify the Problem

The first thing you need to be aware of when troubleshooting a problem is understanding that the symptoms are not the problem.  The actual problem is what’s causing the symptoms to manifest.  To identify the problem, use the following as needed:

• Gather information
• Duplicate the problem, if possible
• Question users
• Identify symptoms
• Determine if anything has changed
• Approach multiple problems individually

Establish a Theory of Probable Cause

Once you think you have successfully researched solutions & identified potential issues that may be causing the problem, it is now time for you to establish a theory of probable cause by doing the following:

• Question the Obvious
  • Sometimes the solution to a problem could be something very simple that just goes unnoticed.
• Consider Multiple Approaches
  • A rule you should abide by is the K.I.S.S. rule:  Keep It Simple Stupid.  Sometimes there are multiple approaches to solving a problem, but it is best to go with the simplest & most easy to implement an approach.
  • Also, think in terms of moving top-to-bottom within the OSI model, or bottom-to-top.
  • Divide & conquer:  sometimes problems arise that may deal with components & their various subsystems.  Divide & conquer allows for you to fix problems in a systematic manner.

Test the Theory to Determine the Cause

Once you believe you have established probable cause, it is now time to test a theory to determine the cause.  This could include things like checking to make sure the correct IP address, subnet mask, & default gateways have been assigned to an end device in order to verify that the end device is able to reach the correct default gateway.  If the theory is confirmed, then it’s time to resolve the problem.  If you come to the conclusion that the theory is incorrect, the next thing you should do is develop a new theory and test it.

Establish a Plan of Action to Resolve the Problem & Identify Potential Effects

Once you have identified the problem & discovered a solution, it’s now time to establish a plan of action to resolve the problem and identify potential effects.  If time permits, you should document your action plan.  The documentation of your action plan can be used as a back-out plan if your hypothesis is incorrect.

Implement the Solution or Escalate as Necessary

If you are responsible for implementing the plan of action, follow it carefully.  Be sure to note any problems with the plan or any additional problems you observe.  If you are not responsible for implementing the plan of action, escalate it to the department that is responsible.

Verify Full System Functionality and, If Applicable, Implement Preventative Measures

Once you have implemented the solution, the next step is to check to make sure that the system or network is fully functional as it is supposed to be with all of the original symptoms gone.  Also, attempt to determine whether your action plan has caused any other issues on the network.

Document Findings, Actions, & Outcomes

When it comes to problems arising in IT, more than likely you are going to encounter similar problems over and over again.  Instead of approaching each problem as if it is the first time you’ve seen the problem, the best approach is to document your findings, lessons learned, actions, and outcomes from each problem you have solved so that you can build a repository of solutions for future problems you are bound to encounter again in the future.  Be sure to add any figures (screen captures, diagrams, photos, etc) that will help you or others solve similar problems next time.  Detailed documentation is your friend when it comes to solving problems in I.T.