What is ARP ?
A. ARP stands for Address Resolution Protocol and was touched on in the previous question as a means of resolving a IP address to an actual physical network card address. All network cards have a unique 48 bit address, that is written as six hexadecimal pairs, e.g. 00-A0-24-7A-01-48, and this address is hard coded into the network card. You can view your network cards hardware address by typing ipconfig /all . Ethernet adapter Elnk31: Description . . . . . . . . : ELNK3 Ethernet Adapter. Physical Address. . . . . . : 00-A0-24-7A-01-48 DHCP Enabled. . . . . . . . : No IP Address. . . . . . . . . : 200.200.200.5 Subnet Mask . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . : 200.200.200.1 Primary WINS Server . . . . : 200.200.50.23 Secondary WINS Server . . . : 200.200.40.190 As discussed in the Subnet question, if a packets destination is on the same local network as the senders, then the sender needs to resolve the destinations IP address into a physical hardware address, oth