[pyx]

The only reply is, "Sir, no excuse sir." It is stressful if you were there.

You're right, I was never at the Citidel. None-the-less, that reply seems a tad INCOMPLETE.
It seems to imply a more complete reply as, "Sir, no excuse sir. I don't know the answer to the question.". And then to say nothing more.

This seems a tad minimalist and appears to lack initiative, imo. While being precise and doing only what is specifically called for (as is necessary in combat) the reply you state still seems lacking.

Initiative within the scope of your orders, unit, responsibility and duty is a quality a thinking officer should have, imo.

My apologies, I still don't see how honestly and honorably admitting ignorance using a respectful tone is stressful.

[HiTech RedNeck]

It sounds like a ritual, nothing more. The point is to get used to being buffeted around by seeming nonsense.

[Cit72]

There is no need to apologize. The answer is still,"Sir, no excuse sir." This is done while you are sitting at attention on the first couples inches of your chair serving the upperclassmen; while thinking about why you squad leader ordered you to report to him after mess; thinking about will I ever get my shoes shinned to the first sgt.'s satisfaction; thinking oh my God, classes start next week; plus many, many other things. The process is a nine month boot camp (the Fourth Class System) while attending college.

[RinaseaofDs]

Enlist and find out (heh, heh.)

The point of being asked questions about stuff you don't know is that with enough intelligence (research your enemy) you can anticipate what they will likely ask. In the future, the hope is avoiding the state of being caught ignorant, or caught unaware.

Even if you are not expected to know, you will hopefully be upbraided for not knowing the answer, and forced to do pushups, sit on the green bench (back up against the wall in a sitting position with no bench underneath you), or something equally as painful. Ignorance, like stupidity, should hurt. Avoiding pain is a fundamental concept to discipline.