I like this question, but I'm wondering what a good interview looks like if someone is completely blind-sided by the question because they don't have a lot (or

I like this question, but I'm wondering what a good interview looks like if someone is completely blind-sided by the question because they don't have a lot (or any) systems experience? I'm imagining an engineer who's experience ends with MySQL so knowledge of stuff like tcb is a definite no. Maybe that's not an issue, because they wouldn't be interviewing for this job if that was the case.