What is a network's default gateway, and how can I find out what mine is?

A gateway is a routing device that passes traffic between different subnets and networks. A computer will know some routes (i.e., the address of each node a packet must go through on the Internet to reach a specific destination), but not the routes to every address on the Internet. A gateway will likewise not have this information, but will at least know the addresses of other gateways it can hand the traffic off to. Your default gateway is on the same subnet as your computer, and is the gateway your computer relies on when it doesn't know how to route traffic.
The default gateway is typically very similar to your IP address, in that many of the numbers may be the same. However, the default gateway is not your IP address. To see what default gateway you are using, follow the steps below for your operating system.

Windows

1. In Windows 7 and Vista, click Start. In the search box, type cmd , and then press Enter. In Windows XP, from the Start menu, click Run... . In the "Open:" field, type cmd , and then click OK.
   
2. This will open the command prompt. At the prompt, enter ipconfig . This will display your network information, including your default gateway.

Mac OS X

1. From the Apple menu, select System Preferences... .
   
   
2. In System Preferences, from the View menu, select Network.
   
   
3. Select the appropriate port. For example, choose Ethernet for broadband connections, AirPort for wireless, or Internal Modem for dial-up.
   
   
4. Click Advanced... , and in the sheet that opens, click the TCP/IP tab. The number next to "Router:" is your default gateway. 

Posted By SonyVegasPro97