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. When I connect to serverfault.com, it maps to an IP address. My computer now has a task of connecting to that IP address. But my computer itself cannot connect to the serverfault IP address. Only the router can. So the task of my computer is to find the IP address associated with the node that will do the routing to the public internet. How does my computer know that a particular IP address in the local network belongs to the router, and is not another computer connected to the network? Is this information configured manually in the operating system itself? Somehow my computer must know that it must send ethernet frames to the router with the expectation that the router will then send the packet to a public IP. How does it know to send it to the router? Is the router's ip address stored in my computer like a key/value pair e.g. "router"="192.168.2.6", so that when I put a public ip address, my computer first knows to connect to 192.168.2.6?