Your question is Troubleshoot System Failure Root Cause. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
How do you troubleshoot a system failure and isolate the root cause?
Describe a practical, structured approach for responding to an active production failure. Explain how you would establish impact, gather evidence, coordinate responders, test hypotheses, restore service safely, and distinguish the trigger from contributing causes. Include the deliverables you would produce during and after the incident.