What is an IP Address?

    This number is an exclusive number, all information technology devices (printers, routers, modems, et al) use which identifies and allows them the ability to communicate with each other on a computer network. There is a standard of communication which is called an Internet Protocol standard (IP). In laymans terms it is the same as your home address. In order for you to receive snail mail at home the sending party must have your correct mailing address (IP address) in your town (network) or you do not receive bills, pizza coupons or your tax refund. The same is true for all equipment on the internet.
    Without this specific address, information cannot be received. IP addresses may either be assigned permanently for an Email server/Business server or a permanent home resident or temporarily, from a pool of available addresses (first come first serve) from your Internet Service Provider. A permanent number may not be available in all areas and may cost extra so be sure to ask your ISP.

Static and Dynamic IP

    Dynamic IP: One that is not static and could change at any time. This type of IP is issued to you from a pool of IP addresses allocated by your ISP or DHCP Server. This is for a large number of customers that do not require the same IP all the time for a variety of reasons. Your computer will automatically get this number as it logs on to the network and saves you the trouble of having to know details regarding the specific network configurations. This number can be assigned to anyone using a dial-up connection, Wireless and High Speed Internet connections. If you need to run your own email server or web server, it would be best to have a static IP.
    Static IP: One that is fixed and never changes. This is in contrast to a dynamic IP which may change at any time. Most ISP's a single static IP or a block of static IP's for a few extra bucks a month.

What is the Difference Between Public and Private IP Addresses?

    Within a private network, computers use addresses excluded by convention from use on the Internet. The difference between a private IP address and a public IP address then, is that private IP addresses are reserved for private networks, and public IP addresses are reserved for the Internet.
    The Internet Assigned Numbers Authority (IANA), a once-autonomous organization, now works within the purview of the Internet Corporation for Assigned Names and Numbers (ICANN). IANA is responsible for overseeing global allocation of IP numbers, among other related protocols. Within the range of publicly available IP addresses are specific, excluded ranges withheld for private network use. These private IP ranges are as follows:
  • 10.0.0.0 … 10.255.255.255
  • 172.16.0.0 … 172.31.255.255
  • 192.168.0.0 … 192.168.255.255
    Computers within a private network are each assigned a unique address in order to exchange files and share resources with one another. The network router, which routes information, will pass data back and forth among the connected computers, using the respective addresses. But how do computers on a private network connect to the Internet?
    Assuming the network has Internet connectivity, the computer connected to the digital subscriber line (DSL) modem is assigned a public IP address by the Internet Service Provider (ISP). This single public IP address is used to identify the network on the Internet. Now the network’s router acts as a gatekeeper between the private network and the public Internet. Using a built-in Network Address Translator (NAT), the router passes requests to the Internet using the assigned public IP address. Returning data is routed back to the public IP address, with the router determining which private IP address requested the information. In essence, the private IP address is daisy-chained to the public IP address through processes in the router.
    A public IP address can be static or dynamic. A static public IP address does not change and is used primarily for hosting webpages or services on the Internet. Some gamers also prefer static IPs for interactive gaming. A dynamic public IP address is chosen from a pool of available addresses and changes each time one connects to the Internet. Most people have a dynamic public IP address, as it is the standard type of public IP address assigned when purchasing Internet connectivity.
    Various freeware programs are available online that will display your computer’s assigned public IP address for you. To see private IP addresses you can open your router’s configuration dialogs, or if using Windows XP, type ipconfig at the command prompt. The command prompt is available through Start -> All Programs -> Accessories -> Command Prompt. To leave the command prompt window, type exit.

How To Determine If Your Computer Is Being Assigned The External IP Address?

    For Windows 2000, XP, and 2003
  • Click Start
  • Click Run
  • Type in cmd and hit ok
  • Type ipconfig and hit enter
    For Vista
  • Click Start
  • Click All Programs expand the Accessories menu
  • In the Accessories menu, Right Click Command Prompt and choose Run as administrator
  • Type ipconfig hit enter
    Results
    If you see an IP that resembles 192.168.n.n then this is an internal IP address assigned by a router. So your router is getting your external IP address. If the IP displayed in the command prompt window matches the one shown on What Is My IP then your computer is being assigned your external IP.

References