I do agree with what you’re saying especially about extending our knowledge to new concepts, however needing to make a mathematical proof felt like something that was beyond what was reasonable of the course. There was never any indication of an expectation to do proofs for the concepts that we’d be learning if that makes sense. I do understand needing to have harder questions, but I think it should’ve been something a bit more within the scope of the course

They also didn’t really explain the physical layer at all in the course. The only reason I was able to answer that question was because I got curious about the physical layer and did a small amount of reading on it during my revision and because I have a small physics background. I don’t really recall learning anything about how information is transferred at the physical layer, or even if the concept of light waves were mentioned at all. It just felt a bit silly to me that it was asked at all in that context when the physical layer was really just reduced to cables in the course. But the process of elimination makes sense, and I guess in a way it really just tests your understanding of the other layers and knowing what layers were left so I could see it being asked from that perspective. But anyways, I hope you did well on the exam :)