The OODA loop for debugging:
Observe: What symptoms exist? Check dashboards, logs, alerts
Orient: Form hypotheses. What could cause these symptoms?
Decide: Pick the most likely hypothesis to test first
Act: Test the hypothesis. Gather more data or attempt a fix
Principles to follow:
- Start broad, narrow down
- Check the simple things first
- Change one thing at a time
- Document what you try
Interview tip: Think out loud. Explain your reasoning. Interviewers want to see your thought process.