5.1 Troubleshooting Methods

Question 1

Step 1: Identify the Problem

Answer 1

Gather information, question users, identify symptoms, determine if anything has changed, and duplicate the problem.

Question 2

Step 2: Establish a Theory of Probable Cause

Answer 2

Question the obvious and consider multiple approaches (OSI Top-to-Bottom, Bottom-to-Top, or Divide and Conquer).

Question 3

Step 3: Test the Theory

Answer 3

Determine if the theory is correct. If confirmed, determine next steps; if failed, establish a new theory or escalate.

Question 4

Step 4: Establish a Plan of Action

Answer 4

Create a specific plan to fix the issue and identify the potential ‘side effects’ or impact of the fix.

Question 5

Step 5: Implement the Solution

Answer 5

Carry out the plan or escalate the issue to a senior engineer if necessary.

Question 6

Step 6: Verify Full System Functionality

Answer 6

Ensure the problem is gone and the rest of the system still works; implement preventive measures (e.g., training, surge protectors).

Question 7

Step 7: Document Findings

Answer 7

Write down the problem, the fix, the outcome, and lessons learned for future reference.

Question 8

OSI Bottom-to-Top Approach

Answer 8

Starting troubleshooting at Layer 1 (Physical/Cables) and moving up to Layer 7 (Application).

Question 9

OSI Top-to-Bottom Approach

Answer 9

Starting troubleshooting at Layer 7 (Application/Software) and moving down to Layer 1 (Physical).

Question 10

Divide and Conquer

Answer 10

Starting troubleshooting at a middle layer (like Layer 3 - Ping) to quickly narrow down if the issue is hardware or software.

Question 11

Question the Obvious

Answer 11

Part of Step 2; checking simple things first (e.g., ‘is it plugged in?’ or ‘is the power switch on?’).

Question 12

Identify Potential Effects

Answer 12

Part of Step 4; considering how a fix might break other things (e.g., ‘If I reboot this switch, who loses connection?’).