http://serverfault.com – Possible Duplicate: How does IPv4 Subnetting Work? For example, I have a computer with a Network Inteface Card (NIC) which is an Ethernet card that is connected by Ethernet cables to a router. There is also another computer with a cable that is connected in another port of the router. This is a Belkin router operating over an Ethernet in the LAN. (HowTos)