What is an IP address?

If you spend any time on the Internet, then you probably heard of the term IP address. But you may be a little confused as to what an IP address exactly is. Here you can find a complete explanation of what IP addresses are and how they relate to the Internet.

All computers that are on a network, such as the Internet, need to have a unique identifier. This unique identifier works in much the same way as a postal address does for mail. This unique identifier is used by other computers on the network to send data to a specific computer.

These days all computers that are on the Internet use the TCP/IP protocol. This is the standard way that computers communicate with each other on the network. According to the TCP/IP protocol the unique identifier used a computer is termed an IP address.

Standards have been established for IP addresses. These are IP version 4 (IPv4) and IP version 6 (IPv6). All of the computers that are on the Internet have an IPv4 address. Many computers now also have an IPv6 address as well.

The IPv4 address is composed of 32 binary bits to create a completely unique address. The IPv4 address is described by four numbers which are separated by dots. A single block of numbers will have a value that ranges between zero and 255. This means that there are a potential 256 values possible combinations for each block. Each of these blocks is used to represent an eight digit binary number, also known as a octet.

An example of an IP address would be

Dynamic IP addresses

There are a potential four billion IPv4 addresses. While this may sound like a lot, considering the number of computers connected to the Internet, if a fixed unique number was assigned to each computer we would soon run out.

This problem is overcome by using what are called dynamic IP addresses. This means that IP addresses are used in rotation. With a dynamic IP you are not always given the same IP address. If an IP address is free then it can be used by a computer. Only some computers, usually businesses, have a reserved IP address.

Subnet addresses

The other way that we overcome the problem of a limited number of IP addresses is using subnet addresses. A subnet is a network of computers which is connected to a bigger network through a router. The subnet can have its own address system. This allows computers that are using the same subnet to communicate with each other without needing to send data over a larger network. For example in your home you might have three computers. The router for your home will be given its own IP address. This creates its own network and all of the devices within that subnet are given separate IP addresses.

All IP addresses on a subnet composed of two parts. These are the network and the node. The network part of the IP address is used to identify the subnet. The node, which is also sometimes called the host, is the individual computer which is connected to the network. Computers know how to distinguish between these two parts of the IP address using a subnet mask.

IPv6 addresses

As noted above using an IPv4 address system there are 4 billion potential combinations for IP addresses. But IPv6 uses a different system which allows us to create a lot more IP addresses. IPv6 is a hexadecimal system rather than binary. A binary system can only have two states. These are one or zero. But with a hexadecimal system there can be 16. This allows us to create a huge amount of potential addresses or 340 undecillion to be the exact.

How to check your IP address

The way that you check what your IP address depends on the operating system that you are using.

If you are using a Mac then you need to click the apple icon in the upper left corner of your screen, scroll down to System Preferences, and then click on the Network icon in the third row. Your IP address will be shown under your connection status.

If you are using Windows XP, then you will need to press the Windows Key plus R which will bring up a command box. After this type CMD and then enter. Follow this by entering >type ipconfig to bring up your IP address.

If you are using either Windows Vista or Windows 7 then from the start menu type CMD in the search bar. When the command box appears >type ipconfig.

For Windows 8 you will need to press the Windows start key, then type CMD followed by enter. After this type ipconfig/all to display the network card settings. Under physical address you will be able to see your IP number.

Bad IP addresses

If the number starts with 169 when you check your IP address, then you will not be able to use the Internet. The 169 address is a way for your router to tell you that it is unable to provide you with a real IP address. One way to fix this problem is to turn off your router for half a minute and then switch it back on. If you’re still having problems and are not able to obtain a proper IP address, then you will need to contact your Internet service provider.