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What is an IP Address?

Last Edit: 09/06/17

bullet Introduction

The most important protocol that provides the communications architecture for the Internet is the Internet Protocol (IP). Each device that connects to the Internet is assigned an IP (Internet Protocol) address: an IP address is a decimal (IPv4) or hexadecimal (IPv6) address that is similar to a telephone number (a number that is assigned to a device located at a physical location). IP addresses are located in the header of IP datagrams (blocks of data also referred to as packets) that are used to transport data across the Internet.

The first standardised IP address released was Version 4 (IPv4): whose specification was published in 1980 and was applied to ARPANET (forerunner to the Internet) in 1983. When the Internet was opened up to civil society in the early 1990's, the amount of IPv4 addresses available (4.3 billion (4,294,967,296)) began to be depleted and was finally exhausted in 2011. Version 6 (IPv6) was designed in the mid-1990's and released in 1998 to solve the problem of IPv4 addresses being depleted; alongside some privacy, security and efficiency improvements.

The Internet Assigned Numbers Authority (IANA) - who control the assignment of IP address block - was fundamental in suggesting that the number of bits in an IP address needed expanding. IP Version 6 was designed by Internet Engineering Task Force (IETF) working groups, and was formalised by December 1998. You may be wondering what happened to IP version 5: that was a failed experimental streaming protocol that was never adopted and was consigned to the protocol dustbin.

IPv4 addresses are a 32-bit decimal number consisting of four units separated by dots: four 8 bits octets (4x8=32 bits). IPv6 addresses are a 128-bit hexadecimal number (comprises numbers and upper / lower case characters) that consists of eight units of four characters separated by colons or double colons: each group of four characters is 16 bits (8x16=128 bits). The following examples show a typical IPv4 and IPv6 address:

In relation to the IPv4 address: the first octet identifies the network and the following three octets identify a local address (host identifier) at the network. IETF and IANA have reserved some IPv4 addresses for special services (Loopback, TEST-NET-1, TEST-NET-2, TEST-NET-3, Private networks etc). IPv4 and IPv6 have not been designed to be compatible, therefore the adoption of IPv6 has taken longer than expected.

bullet IP addresses: In Use

As stated, the typical IP address (Version 4) will look somewhat like the following:

IP addresses can be either static or dynamic: typically a website will have a static IP address; as the website owners will host the service on a specific server. End-users who connect to the Internet through an ISP are typically assigned a new/dynamic IP address every time they connect to the Internet. Dynamic IP addresses are usually assigned by a service provider from a catalog of IP addresses; so, there will be a set limit to the number of possible IP addresses that the user can be assigned.

The IP address system is part of the larger TCP/IP protocol suite: which is basically the backbone software protocol which runs and is the software of the Internet. Without the IP address system, the Internet could not function. The DNS system is a naming system that converts IP addresses to domain names and helps users more easily locate an Internet resource. Users generally do not use IP addresses to locate Internet resources; though they can enter an IP address into Internet apps (like browsers) to locate websites etc.

End-users can attempt to hide and change their IP addresses through connecting to a proxy server; thereby routing their online activity through another computer. The Tor browser is another option for users wishing to mask their IP address. Masking an IP address is useful for users who have concerns about their privacy, and, or, subject to censorship by their Internet Service Provider. However, it should be noted: that users can still be potentially traced through their use of proxy servers and the Tor browser.