[burgerbrain]

Impossible, or seemingly impossible, interview questions are actually quite useful. It can be quite informative to see how the applicant response to such a situation, and what their "Oh shit, wasn't expecting this" emergency problem solving techniques are.

[Helianthus]

Which is another way of saying, messing with people is a respectable interview tactic--see how they react to a little nudge.

[RickHull]

> Which is another way of saying, messing with people is a respectable interview tactic

I don't think so. Rather it's that technology jobs (and others, surely) often confront frustrating, confounding, and even downright impossible tasks. The ability to identify a situation as impossible or otherwise -- to drill down to the point of conflict -- is prized, as well as the ability to keep it together mentally and keep plugging away.