"Checkout is slow." At which level do you look first?
Answer it out loud before you open anything. The value of the flags below is in comparing them to what you actually said — including whether you asked who uses it before naming what you would build it with.
The situation behind the question
Support reports that checkout "feels slow". An engineer has already opened a profiler on the database server and is reading disk-latency graphs. The interviewer asks: "Is that the right level, and how would you decide?"
What it is really testing
Whether the candidate can move between abstraction levels deliberately — architecture, request, service, query, storage — solving at the highest useful level first and going one layer deeper only when evidence sends them there.