IP Address
Overview
An Internet Protocol address (IP address) is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: it identifies the host or network interface, and it provides the location of the host in the network.
IP Addressing
The IP address space is managed globally by the Internet Assigned Numbers Authority (IANA), and by five regional Internet registries (RIRs) responsible in their designated territories for assignment to end users and local Internet registries, such as Internet service providers. IPv4 addresses were distributed by IANA to the RIRs in blocks of approximately 16.8 million addresses each, but have been exhausted at the IANA level since 2011. Only one of the RIRs still has a supply for local assignments in Africa.
IPv4 addresses
Internet Protocol version 4 (IPv4) defines an IP address as a 32-bit number. However, because of the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP (IPv6), using 128 bits for the IP address, was standardized in 1998. IPv4 addresses are canonically represented in dot-decimal notation, which consists of four decimal numbers, each ranging from 0 to 255, separated by dots, e.g., 172.16.254.1.
IPv6 addresses
Internet Protocol Version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion.
Subnetting
In the context of IP addressing, subnetting is the process of dividing a network into two or more networks. It is a method that can be used in both IPv4 and IPv6 networks to create multiple smaller networks within a larger network. Subnetting is used to partition a network's IP address space into smaller, more manageable pieces.
Private addresses
Every class of IP, (A, B & C) has some addresses reserved as Private IP addresses. These IPs can be used within a network, campus, company and are private to it. These addresses cannot be routed on the Internet, so packets containing these private addresses are dropped by the Routers. In order to communicate with the outside world, these IP addresses must have to be translated to some public IP addresses using methods like Network Address Translation (NAT).
Reserved addresses
In IPv4, the addresses 0.0.0.0 and 255.255.255.255 are reserved for network and broadcast addresses respectively. Similarly, in IPv6, the addresses :: and ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff are reserved for unspecified and broadcast addresses respectively.
Dynamic and static IP addresses
Most IP addresses can be categorized as either dynamic or static. Dynamic IP addresses are temporary and are assigned each time a computer accesses the Internet. Static IP addresses are used primarily for hosting websites or services on the Internet. In addition, they are used when anonymity is not a critical concern.
IP address assignment
IP addresses are assigned to a host either dynamically as they join the network, or persistently by configuration of the host hardware or software. Persistent configuration is also known as using a static IP address. In contrast, when a computer's IP address is assigned each time it restarts, this is known as using a dynamic IP address.
Role in routing
IP addresses are binary numbers but are most often expressed in human-readable notations, such as IPv4 addresses expressed in quad-dotted decimal notation or IPv6 addresses expressed in hexadecimal notation. The role of the IP address is to host or network interface identification and location addressing.
