IP addresses Explained
January 8, 2007 6:26am CST
Introduction Every machine on the the Internet has a unique number assigned to it, called an IP address. Without a unique IP address on your machine, you will not be able to communicate with other devices, users, and computers on the Internet. You can look at your IP address as if it were a telephone number, each one being unique and used to identify a way to reach you and only you. The Address Itself An IP address always consists of 4 numbers seperated by periods, with the numbers having a possible range of 0 through 255. An example of how an ip address appears is: 192.168.1.10 This representation of an IP address is called decimal notation and is what is generally used by humans to refer to an IP address for readability purposes. With the ranges for each number being between 0 and 255 there are a total 4,294,967,296 possible IP addreses. Out of these addresses there are 3 special ranged that are reserved for special purposes. The first is the 0.0.0.0 address and refers to the default network and the 255.255.255.255 address which is called the broadcast address. These addresses are used for routing, which will not be covered in this tutorial. The third address, 127.0.0.1, is the loopback address, and refers to your machine. Whenever you see, 127.0.0.1, you are actually referring to your own machine. That means if you clicked on this link, http://127.0.0.1, you are actually trying to connect to your own computer, and unless you have a webserver running, you will get a connection error. There are some guidelines to to how IP address can appear, though. The four numbers must be between 0 and 255, and the IP address of 0.0.0.0 and 255.255.255.255 are reserved, and are not considered usable IP addresses. IP addresses must be unique for each computer connected to a network. That means that if you have two computers on your network, each must have a different IP address to be able to communicate with each other. If by accident the same IP address is assigned to two computers, then those computers would have what is called an "IP Conflict" and not be able to communicate with each other.