Which Troubleshooting Step Checks OSI Model Layers?

N10-009 By islever Editorial Last updated

Short answer

A Establish a theory.

Question

Which of the following steps of the troubleshooting methodology would most likely include checking through each level of the OSI model after the problem has been identified?
  1. Establish a theory. Correct Answer
  2. Implement the solution.
  3. Create a plan of action.
  4. Verify functionality.

Key Takeaways

This question tests your ability to sequence CompTIA's troubleshooting steps; the trap is confusing OSI-model checks with the later 'Verify functionality' step, but the OSI approach is explicitly part of establishing a theory.

Learn which step in CompTIA's troubleshooting methodology involves checking OSI model layers. Community votes favor 'Establish a theory' (A) as the correct next step after problem identification, supported by the official CompTIA methodology.

Common mistake: D. Verify functionality — 29% of voters chose this because verification may involve testing OSI layers, but verification occurs after implementing a solution, not immediately after problem identification.

Expert Analysis

Why the Answer Is Correct

A is correct because CompTIA's troubleshooting methodology places 'Establish a theory of probable cause' as the second step, immediately after 'Identify the problem.' The official blog states that during this phase you consider multiple approaches, including top-to-bottom or bottom-to-top for layered technologies such as networks. As commenter Nyang2 noted, the CompTIA blog lists 'Establish a theory of probable cause' as step 2, which directly matches the question's wording.

Why the Other Options Are Wrong

B (Implement the solution) and C (Create a plan of action) occur later in the methodology, after the theory has been tested and a cause confirmed. D (Verify functionality) is step six, which happens after the solution has been implemented and is not the step where you initially check OSI layers. Commenter [3] argued for D, but that misreads the timeline—OSI-model checking is part of narrowing down probable causes, not the final verification.

Community Comment Notes

Commenters overwhelmingly supported A, with several quoting the official CompTIA steps. One commenter linked to the CompTIA troubleshooting methodology page, reinforcing that 'Establish a theory' is the step that mentions top-to-bottom or bottom-to-top OSI analysis. A smaller group suggested C, viewing a plan that checks each OSI layer as a 'plan of action,' but the official step explicitly places this activity in 'Establish a theory,' not in the subsequent planning phase.

Official Reference

https://www.comptia.org/blog/troubleshooting-methodology

This link opens the official vendor documentation in a new tab.

Exam Strategy

Memorize the six-step order: Identify the problem → Establish a theory → Test the theory → Plan an action → Implement the solution → Verify functionality. When the question mentions 'after the problem has been identified,' your anchor is step 2; always look for the step that appears right after the action described.

Community Votes

A
70%
D
30%

70% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 14 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 14

  1. a484b2b 👍 19
    I just passed N10-009 this past weekend, 11.9.24 using these questions. I studied the 159 questions and they were a lifesaver. I also got all 6 scenario questions, the first one was very complicated and I gave up and moved on. I saved the scenarios for last and they took 50 min to go through. Study all 159 questions the answers given. It's worth it. I got a 836 for my score even not doing well with a couple of the scenario questions!!
  2. Nyang2 👍 10
    https://www.comptia.org/blog/troubleshooting-methodology 1. Identify the problem 2. Establish a theory of probable cause ===> Answer : A 3. Test the theory to determine the cause 4. Establish a plan of action to resolve the problem and identify potential effects 5. Implement the solution or escalate as necessary 6. Verify full system functionality and, if applicable, implement preventive measures 7. Document findings, actions, outcomes and lessons learned
  3. Dennizje 👍 5 Answered D
    Correction, it's D Verifying using the OSI model is explicitly mentioned in the troubleshooting methodology.
  4. KD603 👍 3 Answered A
    The next step after identifying the problem is establishing a theory of probable cause which can include considering multiple approaches: top-to-bottom or bottom-to-top OSI model approaches. Verify functionality would include OSI model but only after implementing the solution which hasn't happened in this question
  5. chupapi_001 👍 3 Answered A
    The correct answer is A: Establish a theory.
Show 9 more comments
  1. b82faaf 👍 2 Answered A
    A. Establish a theory According to the CompTIA troubleshooting methodology, once the problem has been identified, the next step is to establish a theory of probable cause. This involves systematically analyzing the problem and narrowing down potential causes. Checking through each level of the OSI model is a common practice at this stage to identify where the issue might be occurring.
  2. Dennizje 👍 2 Answered A
    Notice or identify problem, hypothesize possible cause, look for problem testing the possible cause, fix the problem, only then you verify the functionality.
  3. PepeProblemas198753567 👍 2 Answered A
    The correct answer is A (check Nyang2´s answer)
  4. 93831b0 👍 1 Answered C
    Here is my view on this one. Designing a methodical process to check each layer of the OSI model falls under "Create a plan of action." This step involves developing a thorough plan that includes troubleshooting each OSI layer to pinpoint the issue. You can look at it like drawing up a detailed blueprint for troubleshooting. You're outlining how you'll approach each layer if necessary.
  5. ec80b38 👍 1
    The reason it is said to be A is because from comptias website under establish a theory "The steps in this phase are: Questioning the obvious to identify the cause of the problem Considering multiple approaches, including top-to-bottom or bottom-to-top for layered technologies (such as networks)"
  6. Intel_Geek 👍 1 Answered D
    When verifying functionality after identifying a network problem, Checking each layer of the OSI model would be good to make sure the issue is fully resolved at every level of communication - please correct me if I am wrong
  7. lord_darth_vader 👍 2 Answered A
    A. Establish a theory
  8. Hayder81 👍 1
    Establish a theory chat gpt
  9. LilJuneBug 👍 1
    is the answer not D?

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