Normally, when I don't know a response or an answer to a question, I'll try my best to figure it out on the dot, which 9 times out of 10 isn't really possible in some scenarios. But I'll try to answer it to the best of my ability or I'll phrase it in a sense of like, well, I'm not too sure or from my experience or based on my knowledge, this is how I can answer that question. If they're wanting an exact, then I'll go to whoever does know it, whether that's the higher up or another coworker or whatnot, and I'll talk to them about that question and see what the answer is and then go back and answer the question thoroughly. That way, we're not just leaving whoever is asking that question in the dark.