The approach.
THE FOUR QUESTIONS
What exactly fails? When did it start? What changed? Who is affected?
WHY THOSE
They eliminate most possibilities immediately.
WHAT TO ESTABLISH NEXT
Whether it affects one device or all Wired as well as wireless One destination or everything Consistently or intermittently
HOW TO WORK
From the bottom upward.
Link, address, gateway, name resolution, then the service.
WHY
A lower-layer problem makes everything above it fail.
WHAT TO CHANGE
One thing at a time, testing after each.
WHY
Otherwise you never learn which change fixed it, and you may cause new faults.
WHAT TO RECORD
What you tried and what happened.
WHAT TO DO BEFORE ESCALATING
Establish and write down what you have ruled out.
WHAT THAT ACHIEVES
A faster resolution, and a report that is taken seriously.
WHAT MOST PROBLEMS TURN OUT TO BE
Something that changed, and something simpler than expected.
