What would you suggest as the best way to deal with students' questions that seem irrelevant to their upcoming exams?
When I was studying for my university-entrance exam, I came across a couple of university-level integration questions that I couldn't answer. When I asked my school teacher for help, he advised me to ignore them as they are irrelevant to the exam.
In another incident, when approached for help with a question from a Physics textbook, my school teacher said that the question is important but he didn't know how to answer it. I eventually got the answer from the educational service of a state radio channel, then the same question appeared in the following year's physics exam.
I think that in addition to exam-related knowledge, having a healthy curiosity about our teaching subject is important when assisting students with relatively novel issues.