N10-009 - Network Troubleshooting (24% of the exam) - Section 5.1

Explain the network troubleshooting methodology, from identifying the problem through establishing a theory, testing, resolving, and documenting.

Explain the structured CompTIA troubleshooting methodology in order: identify the problem, establish a theory of probable cause, test the theory, establish and implement a plan of action, verify full functionality, and document findings. Recognise that steps proceed top-down or bottom-up through the OSI layers and that a change must be documented even after the symptom clears.

Troubleshooting methodologyTheory of probable causeVerify functionalityDocument findings

Practice question for this objective

Free sampleNetwork Troubleshootingeasy

A technician has just established a theory of probable cause for an intermittent connectivity fault. According to the CompTIA seven-step methodology, what is the next step?

AEstablish a plan of action to resolve the problem and identify any potential effects.
BImplement the solution, or escalate the change to another team where that is required.
CTest the theory to determine whether the suspected cause is actually responsible. Correct
DDocument the findings, the actions taken, and the outcomes for future reference.

After establishing a theory of probable cause, the next methodology step is to test the theory to determine the cause. The seven steps run in a fixed order: identify the problem, establish a theory, test the theory, plan a course of action, implement, verify functionality, then document; testing directly follows the theory.

Why A is wrong: Planning a course of action comes only after the theory has been tested and confirmed, so it is two steps too early here.

Why B is wrong: Implementing a solution is a later step that follows planning; a fix should not be applied while the theory is still untested.

Why C is correct: Once a theory is established, the methodology requires testing it to confirm or rule out the suspected cause before any fix is planned.

Why D is wrong: Documenting findings is the final step and happens after the problem is resolved and full functionality is verified.

See more N10-009 practice questions, answers explained.

Exam traps in Network Troubleshooting

Answers that look right on this material and are not. Each one is a distractor from a different question in the N10-009 bank for this domain.

Implement the solution by hard-coding both interfaces to the same speed and duplex.
Why it is wrong: This is the eventual corrective action and feels efficient, but implementing a change comes only after the theory has been tested and a plan of action has been established.
Test the theory again with a different cable tester to be doubly certain of the result.
Why it is wrong: Retesting reflects a good verification instinct, but the theory has already been confirmed, so repeating the test is not the prescribed next step.
Implement the original solution anyway and then monitor whether the fault recurs.
Why it is wrong: Pushing ahead feels like progress, but a fix built on a disproven theory has no confirmed cause and risks making an unrelated change.

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