If I was hiring a network technician, I definitely wouldnt hire someone who didn't know what ARP is. It's too easy and fundamental to the field. It took all of like 3 weeks at the trade school I attended to cover IPv4, MAC, ARP, basic routing protocols, TCP, and UDP, and we were definitely chilling. Understanding those things isn't complicated. You just need to know what computers are, and what "networks" are, then it all very easily clicks into place.