I've done these sorts of questions before and the point (more me at least) was two-fold:
1. Do they understand the basic machinery of a web application (assuming the job is about building web applications)?
2. Can they take a vague problem ("the page is loading slow") they might get from an actual non-technical user and drill down to identify what precisely the issue is? Is it DNS? Is it a proxy server/load balancer? Is their latency at the DB layer? How would you tell the difference between all of these?
I'll take high level architecture design and software coding problems over live debugging any day. Which is kind of my point. This kind of session is going to potentially weed out candidates with different strengths & a good team is a mix of a variety of strengths.
1. Do they understand the basic machinery of a web application (assuming the job is about building web applications)?
2. Can they take a vague problem ("the page is loading slow") they might get from an actual non-technical user and drill down to identify what precisely the issue is? Is it DNS? Is it a proxy server/load balancer? Is their latency at the DB layer? How would you tell the difference between all of these?