Not sure I'd agree about it being esoteric. Understanding or at least knowing about ARP is still very much essential for people in networking. arping is a very

Not sure I'd agree about it being esoteric. Understanding or at least knowing about ARP is still very much essential for people in networking. arping is a very useful tool for seeing if machines on the same network segment are up and just not responding to ICMP pings. Anyone looking at tcpdump/Wireshark dumps will run into it sooner or latter. It is true that software engineers may sooner run into it when debugging their home network than their application though as cloud and traditional networks are very different.