> "Look, you know as well as I that this job has nothing -- as in, nothing whatsoever -- to do with actually building production-grade database servers. Or anything even remotely analogous to it. Debugging that tangled mess of poorly conceived, never-reviewed JSON APIs left behind by the other developer (while you were pestering them about 'disruption' and 'just needing to get this thing to market') is more like it."

I was asked a similar type of question at Microsoft once about operating systems. I don't think the interviewer expected that I know the answer to what he was asking but rather explain what I do know, and then based off my limited understanding work backwards to see what might be done and what tradeoffs are being considered.

At least that's what the interviewer said to me when I responded with "Oh God I have no idea I have never done anything like that before." For what it's worth I did get the offer despite not knowing anything.

That being said, I did interview at another company where I was asked something that I guess the interviewer thought was very basic and I responded with something similar. His advice to me was to never say I don't know something, which I don't really agree with. I didn't pass that one.