Ethernet is far more than plugging in a cable and getting network access. This deep dive explains how Ethernet actually works, from MAC addresses and frame structure to switching, CAM tables, VLANs, ARP, STP, MTU/MSS, Wireshark captures, offloading, virtualization and modern data-center networking. It also covers the details most guides skip, including how MAC addresses change across routed hops and why packet captures don’t always represent exactly what crossed the wire.