All About Your IP Address

Has somebody ever asked you what your IP Address is? Do you know what one is? Did you know you can physically locate a computer by its IP Address? Once you learn your computers' IP Address you can do all kinds of things with your computer and people all over the world.

First, let us find out what an IP Address, or Internet Protocol Address, is. The short answer is: it's a number that each computer is assigned when they [computers] enter a network of other computers. This number is actually a set of four numbers connected with periods, so for example, 192.168.0.1 is an IP address.

Now let's look at how your computer is assigned an IP Address. Whenever you connect to a network -- any network, whether it is a private at home network of three computers, or a corporate network comprised of hundreds of computers, or even the Internet with millions of computers interconnected, your computer is assigned an IP Address. There are two methods to assigning an IP Address. The first is called Dynamic. Every time you connect to the network, your computer is automatically assigned an IP Address from a pool of addresses. For now, just remember that this number is only a temporary assignment. The second method is called Static. Usually only System Administrators of business corporations will use this method. Each and every computer on a single network must have a unique IP Address.

As I explained earlier, an IP Address is comprised of four numbers connected with a period. Each of these four numbers can be between 0 and 255. Remember, since we're dealing with computers, and a computers' native language is binary (a numerical system using only ones and zeros), each number represents a byte (or eight digits of binary).

Only the first of these four numbers are significant. This first number determines the Class of the network, while the next two numbers may refer the subnet, or sub-network (a network inside of a bigger network of computers). The final number is your host identifier, and must be unique.

There are five classes of IP Addresses; each one fills a specific purpose, so you can easily tell which type of network a computer is connected to.

Class A refers to addresses from 0.0.0.0 to 127.255.255.255. This is denoted by the very first bit (the left most digit in a binary byte) as being set to a 0. This class can hold the most number of computers on a single network, but has the smallest number of networks it can hold, and typically is only reserved for large corporation networks or government networks. Note that the IP Address of 127.0.0.1 is a special address referred to as a Loopback, and is used for internal communication and testing inside your computer (whether connected to a network or not).

Class B refers to addresses from 128.0.0.0 to 191.255.255.255. This is denoted by the first two bits being set as 1 and 0. This class can hold a substantially larger number of networks (upwards of sixteen thousand), and has a wide number of computers on each network (towards sixty-five thousand). This is a good option for institutions that have a need for lots of networks, but still have a lot of computers on each network, like hospitals.

Class C refers to addresses from 192.0.0.0 to 223.255.255.255. This is denoted by the first three bits being set as 1, 1 and 0. This class allows for the most number of networks, but the least number of computers on each network (only allowing 256 computers per network).

Class D refers to addresses from 224.0.0.0 to 239.255.255.255. This is denoted by the first four bits being set as 1, 1, 1 and 0. There are no host computers in this group. Each computer shares an IP Address with the group it's assigned. This class is reserved for Multicasting (the operation of communicating to multiple, but not all computers on a network at the same time).

Class E refers to addresses from 240.0.0.0 to 255.255.255.255. This is denoted by the first four bits being set as 1, 1, 1, and 1. This class is not used, and is reserved for experimental purposes.

Within the first three classes, are a set of special address ranges, called Private Network Addresses, that anybody may assign and use. The Class A range is between 10,255.255.255. Mostly only large corporations use this range. The Class B range is between 172.16.0.0 and 172.31.255.255. Most small businesses use this range. Finally Class C has its own range of 192.168.0.0 to 192.168.255.255. Mostly only private users will use this range.

For the most part IP addresses are assigned by ISP's (Internet Service Providers) which is regulated by the Internet Assigned Numbers Authority, which works with the five Regional Internet Registrars around the world to ensure IP addresses are segregated by location.

Now that we know what an IP Address is, let's determine how to find out what your IP Address is. There are two methods for doing this, and each will give you a different number. The first way, will tell you what your Internal IP Address is, and is handy in knowing if you are on a network and want to play a game for example. To find your IP Address, you need to open up something called the Command Prompt. To do this, click on your Start button, and click on Run. Then type in CMD. Once there, type in the command: ipconfig. This will give you some other information, but most notably, the IP Address you want.

The second method is using your internet browser, and will tell you your Public IP Address. To do this, simply go to the address http://www.whatismyip.com and in big bold numbers, you will see your IP Address. This is most likely the Address you want since you need it for online games, chat programs, or if you need to connect to another network across the globe.

Sources:
* http://en.wikipedia.org/wiki/IP_address
* http://en.wikipedia.org/wiki/Classful_network
* http://www.paessler.com/info/ip_address_basics_ii