LAN: Ethernet-3
Each computer is designated by an unique address: the hardware address
The hardware address consists of 6 bytes noted as “AA:00:04:12:23:34”
The first 3 bytes indicates the manufacturer of the interface
To obtain the hardware address of a computer known by his IP address, ARP (Address Resolution Protocol) is used, based on a broadcast: “who is A.B.C.D ?”