By default, all Windows operating systems use the TCP/IP protocol suite to
communicate with each other through network devices. Any computer network adaptor using TCP/IP requires
3 things to communicate with other computers: An IP address, a subnet mask
for that IP address, and a default gateway. These terms will be defined
in a moment. First, though, an idea of how a TCP/IP network works logically.
When you give a computer an IP address, you identify
the network which it is a member of, and give it an identification number
within that network. A computer in a given network can communicate with any
other computer that is local to it (in the same network), provided there
is a way for information to pass between them (network cables, wireless network, etc.).
Computers in a network cannot, however, communicate with computers in a different network
(remote network) directly, even if they are physically connected to each other via cables.
where the default gateway comes in. A gateway is defined as a path
out of the local network to other remote networks. A gateway can be
a number of things physically, such as a DSL/cable router for your local
network, a Windows server computer with multiple network adaptors split between different networks, etc. Gateways must all share one thing in common though. They are connected
to at least 2 networks, and have the ability to pass traffic between them.
default gateway assigned to a network adaptor is sent all traffic that does not
belong in the local network. As an example of this, say you have a DSL Internet
connection. When you connect to the Internet, you are provided with a default
gateway assigned by your service provider. When you attempt to connect to a site
on the Internet, the URL you type in (say www.pcstats.com) is converted into an IP address by your Internet provider.
Since this address is not
going to be in your local network, the network adaptor in your computer
forwards the request for the web page to its default gateway, your service provider.
point, your request will be passed from network to network through the internet
until it reaches the local network of www.pcstats.com and the data needed to display
the web page starts its way back through the internet to your IP address.
That isn't where IP addresses
stop, as you'll discover next.