Why we need IP addresses.
Just like the way you need a unique address to mail a letter to, so does every device on a network require a unique address so that computers can communicate with them. The TCP/IP protocol is the most used standard in networking (including the Internet). The TCP/IP protocol uses IP addresses to uniquely identify each connected device.
Currently, IP addresses are formed using IP Version 4 (IPv4) and IP version 6 (IPv6) standards. The IPv6 is the latest, therefore, any computer that communicates using the TCP/IP protocol must have the earlier IPv4 address, while the IPv6 address may be used optionally. Technically, the two IP address versions are formed as follows:
Formed by using 32 binary bits to generate one unique network address. It is made up of four digit sections that are separated by dots, where a section represents a base-2 number (2x), for example: 18.104.22.168
Formed by using 128 binary bits to generate one unique network address. It is made up of eight digit sections that are separated by colons, where a section represents a base-16 number (16x)/sixteen-digit binary/hexadecimal figure, for example: 1980:a9b1:0000:1102:2302:0000:1620:3821. The address is commonly shortened by removing a section that contains only zeros, for example, the preceding example can be shortened to: 1980:a9b1::1102:2302::1620:3821.
How Does My Computer Get its IP Address?
You can assign your computer’s IP address manually or let it be generated automatically. A manual IP address is known as a static IP address, while an automatically generated one is known as a dynamic IP address. The static IP address requires extensive network TCP/IP configuration and is less popular than the dynamic IP address because it increases the chance of creating address conflicts and ultimately network clogs. The dynamic IP addressing technique is determined by the Dynamic Host Configuration Protocol (DHCP). In general, when you connect to the internet, your ISP has a DHCP server that assigns an IP address automatically to your PC for a certain period, which can be released and renewed by executing specific commands. See more about a static and a dynamic IP address.
Address Range and Restrictions
You should first understand that the commonly used IPv4 addressing system is made up of four eight-digit binary sections, where each can be represented by binary numbers that run from 00000000 to 11111111 (or 0 to 255 in the conventional decimal system). Therefore an IPv4 address may fall anywhere between 0.0.0.0 and 255.255.255.255. The TCP/IP protocol is formulated by the Internet Assigned Numbers Authority (IANA) in a manner that restricts the use of certain addresses. For example:
This address represents a network. You cannot assign this address to your computer because it is used by TCP/IP to signify the presence of a network.
This is the network broadcast address. A message that is sent to this address will be received by every device that is connected to the network.
This address represents a device itself. In common networking terms it is referred to as the HOST. It is used by a device to send messages to itself disregarding its network connection status.
169.254.0.1 – 169.254.255.254
Any address that falls within this range is referred to as an Automatic Private IP Address (APIPA). Your computer will only be referred to by an address within this range if the DHCP server fails to assign a suitable address.
IANA restricts the use of IP addresses that are reserved for subnets. In this case the subnet is defined as a sub-network or a network within a network that communicates with other networks through a router. The devices on the subnet have their own address range so that the router can send signals to the concerned devices without having to access outside networks, thus saving time. Networks that use the TCP/IP protocol are allowed to have several interconnected subnets whereby the subnet addressing system will make it easier to route traffic. The IP addresses reserved for subnets are described below:
10.0.0.0 – 10.255.255.255
This is the Class A subnet range which runs from 22.214.171.124 – 127.0.0.0 and the first addressing bit is 0.
172.16.0.0 – 172.31.255.255
This is the Class B subnet range which runs from 126.96.36.199 – 188.8.131.52 and the first addressing bit is 0.
192.168.0.0 – 192.168.255.255
This is the Class C subnet range which runs from 192.0.0.0 – 184.108.40.206 and the first addressing bits are 110.
This is the subnet range which was formerly referred to as Class D and whose addresses run from 220.127.116.11 – 18.104.22.168 and the first addressing bits are 1110.
This is the subnet range which was formerly referred to as Class E and whose addresses run from 240.0.0.0 – 254.255.255.254. It is reserved by IANA for future use.
An Internet Connection Scenario
Let us see how the concepts discussed earlier can be observed from a connection between your computer and the Internet. When you get connected to the Internet using a computer, most probably, you are doing it through an Internet Service Provider (ISP). In a case where only one computer in your home/office is connected to the Internet, the computer’s IP address is directly assigned by the ISP. See the difference between a global IP and a local IP address.
If you connect multiple devices to the Internet using a router (Wi-Fi or wired) as the gateway, the router will be directly assigned an IP address by the ISP. The router will automatically generate and monitor a subnet of all the devices that use it to access the Internet. To confirm this, check your computer’s IP address if you are part of a network that is connected to the Internet and you will notice that it falls within the subnet ranges discussed earlier.
When your computer is connected to the Internet through a subnet, its IP address will contain two distinct parts. The network and node sections, where the network section will refer to the subnet while the node section will refer to your computer. To identify other devices on a network, a computer’s networking card will interpret an IP address using a subnet mask. The subnet mask’s notation resembles that of an IP address but is used to separate the IP address’s network and node section.
To know the IP address of your computer, you can simply go the command prompt (type “command” on the search dialog box from Windows 7 menu) and run the command “IPconfig”. See a list of network troubleshooting commands.