5.1 - The network troubleshooting methodology
Network+ N10-009 objective 5.1 is the CompTIA troubleshooting methodology, and the exam tests the order closely. The steps are: identify the problem (gather information, question users, determine what changed); establish a theory of probable cause; test the theory to determine the cause, and if it fails, establish a new theory or escalate; establish a plan of action to resolve the problem and identify effects; implement the solution or escalate; verify full system functionality and, if applicable, implement preventive measures; and finally document findings, actions and outcomes. Right after identifying the problem you establish a theory, and right after a confirmed theory you test it. Expect questions that give one step and ask what comes immediately before or after, or name the first or final step - so memorise the sequence exactly.
Order: 1) Identify 2) Theory of probable cause 3) Test the theory 4) Plan of action 5) Implement 6) Verify + prevent 7) Document. After identify = theory; after confirmed theory = test it.
Practice questions
1. What is the first step of the CompTIA troubleshooting methodology?
- Identify the problem (correct answer)
- Establish a theory of cause
- Test the theory
- Document the findings
Step 1 is Identify the problem (gather info, question users, note changes). Then theory, test, plan, implement, verify, and document. Documentation is last.
2. After fixing an issue and verifying the fix, what is the final methodology step?
- Establish a new theory of cause
- Document findings and actions (correct answer)
- Escalate the issue to the vendor
- Reboot the affected device again
The final step is to document findings, actions and outcomes. This closes the loop and helps future troubleshooting. Verification comes just before documentation.
3. After identifying a problem, what is the next step in the CompTIA methodology?
- Document the outcome and actions taken
- Verify full system functionality first
- Implement the corrective solution now
- Establish a theory of probable cause (correct answer)
After identifying the problem, you establish a theory of probable cause, then test it. Implementation and verification come later; documentation is last.
4. Following the troubleshooting methodology, what comes right after establishing a theory of probable cause?
- Document findings
- Implement the solution
- Test the theory (correct answer)
- Identify the problem
After forming a theory of probable cause you test it to confirm or reject before acting. Only once confirmed do you plan and implement; documentation is the final step.
5. After confirming a fix works, which methodology step comes next?
- Establish a new theory of probable cause
- Document findings and outcomes (correct answer)
- Escalate the case to the hardware vendor
- Reboot every device on the segment
After verifying full functionality (and preventive measures), the final step is to document findings, actions and outcomes. Establishing a theory is early; escalation and reboots are not methodology steps.
6. Several users report the same outage. Before changing anything, what should you do first?
- Gather information, identify scope (correct answer)
- Replace the core switch immediately
- Reboot the edge firewall right away
- Roll back last month's approved change
Step one is to identify the problem: gather information, define who/what is affected and scope it. Swapping hardware or rebooting before understanding the issue risks making things worse.