An Internet Protocol address (IP address) is a number tag associated with every device in a network that uses the given Internet Protocol server for communication. It is used principally to identify the network interface and to obtain the address of the host’s location. It is used as a reference point to identify a particular device to which data can then be sent, or received from. It is quite similar to the role that your name and address play when you are sending or receiving snail-mail.
The IP address was originally designed to be a 32-bit number system, known as the Internet Protocol Version 4 (IPv4), usually represented in what is known as dotted decimal format such as 220.127.116.11, this being the system that is understood by computers. The four sections that are formed due to the dots are known as “octets” and can each be numbered from 0-255, thereby creating a total of 4,294,967,296 potentially unique IP Addresses. Plenty of these IP addresses have been reserved for private networking, which facilitates millions of users across the planet to construct and administer private networks with one of the many available networking ready devices at their disposal.
These private addresses in the ranges of 192.168.0.0 – 192.168.255.255, 10.0.0.0 – 10.255.255.255& 172.16.0.0 – 172.31.255.255 can be used uniquely by any device which is a part of a network. These addresses cannot be used by more than one device at the same time as they are “non-routable addresses” and the routers that transmit are specially programmed to recognize these addresses. The routers will ensure that the data meant for a private address will not be forwarded if there are multiple devices with the same address. Hence, a device always requires a unique address from the given range so that the local router can perform “Network Address Translation”.
Network Address Translation (NAT) is a process by which a local router converts a private IP Address into a public one so that exchange of data can happen over the internet. When some data is received by the local router, the reverse conversion from a real IP Address to a private one is carried out in order to transmit the data to the device. Private addresses can also be used for effective local networking by allocating addresses that are meant exclusively for certain universities or organizations.
An IP addresses was initially interpreted in two parts: network number portion and host number portion. The octet to the leftmost in an address was designated as the network number and the remaining bits were called the host identifiers and were used for numbering the devices within a network. However, this was inadequate and internet addressing specification was revised with the introduction of “classful network architecture” which allowed for a larger number of individual network assignments and a fine-grained sub-network design. According to this architecture, the first three bits of the leftmost octet of an IP address were defined as the “class” of the address, one of A, B, or C, and depending on the class derived, the network identification was based on octet boundary segments of the entire address. This ensures that the necessity for allocation of unique IP addresses to different devices is satisfied.