[bitexploder]

Same thing when I interview people. I don’t know is a sign of confidence to me. It is the right answer in so many situations. Unless you have a reasonable shot at deriving the answer on the spot, it’s what more people should be saying, and not only in interviews.

[cs02rm0]

Agree. Although a better answer is (sometimes) I don't know, but... and some indication of how they might get to the answer.

[bitexploder]

That’s my usual prompt. How much do you know about the domain, how long will it take you to know.