Testing Theories and Making a Plan
Confirm the cause, then plan and apply a fix carefully.
From Theory to Test
Once you have a theory of probable cause, you must test it before fixing anything. Testing confirms whether your guess is right and prevents wasted effort or accidental damage. The principle is simple: prove the cause, then plan the cure. Jumping to a fix on an unconfirmed theory is one of the most common troubleshooting mistakes.
Designing a Good Test
A good test isolates one variable and gives a clear yes-or-no answer. If you suspect a bad cable, swap it for a known-good one and see if the link returns. If you suspect DNS, ping the destination by IP, then by name. Each test should confirm or eliminate exactly one theory, so the result is unambiguous.
All lessons in this course
- The Structured Troubleshooting Steps
- Identifying and Defining the Problem
- Testing Theories and Making a Plan
- Verifying and Documenting the Fix