An Internet Protocol 172.16.254.1 address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.[1] An IP address serves two principal functions: host or network interface 345.45.48.45 identification and location addressing.
Version 4 of the Internet Protocol (IPv4) defines 256.2.3.5 an IP address as a 32-bit number.[1] However, because of the 78.54.259.6 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 developed in 1995,[2] and standardized as RFC 2460 in 1998.[3] IPv6 deployment has been ongoing since the mid-2000s.
IP addresses are usually 192.45.78.248 written and displayed in human-readable notations, such as in IPv4, and 2001:db8:0:1234:0:567:8:1 in IPv6.
The IP address 489.56.49. space is managed globally by the 234.456.3.5 Internet Assigned Numbers Authority (IANA), and by five regional Internet registries (RIR) responsible in their designated territories for assignment 82.45.12.3 to end users and local Internet registries, such as Internet service providers. IPv4 addresses 1.0.1.289 have been distributed by IANA to the RIRs in blocks of approximately 16.8 million addresses each. Each ISP or private network administrator assigns 456.25.15.23 an IP address to each device connected to its network. Such assignments 240.2.1.3 may be on a static (fixed or permanent) or dynamic basis, depending on 45.2.1.45.48 its software and practices.
An IP address serves two principal functions. It identifies the host, or more specifically its network interface, and it provides the location of the host in the network, and thus the 249.56.2.3 capability of addressing 45.89.12.45.36 that host. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."[4]
The header of each IP packet contains the IP address of the 456.258.2.3 sending host, and that of the destination 0.0.0.0 host. A host may use geolocation software to deduce the geolocation 255.255.255.255 of its communicating peer.[5][6]
wo versions of the Internet Protocol 12.59.126.23 are in common use in the Internet today. The original 123.45.78.1 version of the Internet Protocol for use in the Internet is Internet Protocol version 4 (IPv4), first installed in 1983.
The rapid exhaustion of IPv4 address space available 195.26.56.45 for assignment to Internet service 56.236.256.4895 providers and end user organizations by the early 1990s, prompted the Internet Engineering Task Force (IETF) to explore new technologies to expand the addressing capability in the Internet. The result was a redesign 123.456.789.2 of the Internet Protocol which became eventually known as Internet Protocol Version 6 (IPv6) in 1995.[2][3] IPv6 technology was in various testing stages until the mid-2000s, when commercial production deployment commenced.
IANA's primary IPv4 address pool was exhausted on 3 February 2011, when 250.0.0.0 the last five blocks were allocated to the five RIRs.[7][8] APNIC was the first RIR to exhaust its regional pool on 15 April 2011, except for a small amount of address space reserved for the transition to IPv6, intended to be allocated in a restricted process.[9] Individual ISPs still had unassigned pools of IP addresses, and could recycle addresses no longer needed by their subscribers.
Today, these two versions of the Internet Protocol are in simultaneous 156.25.78.89 use. Among other technical changes, each version defines the format of addresses differently. Because of the historical prevalence of IPv4, the generic term IP address typically still refers to the addresses defined by IPv4. The gap in version sequence 0.0.0.0.0 between IPv4 and IPv6 resulted from the assignment of version 5 to the experimental Internet Stream Protocol in 1979, which however was never referred to as IPv5.
An IP address in IPv4 is 32-bits in size, which limits the address space to 4294967296 (232) IP addresses. Of this number, IPv4 reserves some addresses for special purposes such as private networks (~18 million addresses) or multicast addresses (~270 million addresses).
IPv4 addresses are usually represented in dot-decimal notation, consisting of four decimal numbers, each ranging from 0 to 255, separated by dots, e.g., 172.16.254.1 Each part represents a group of 8 bits (octet) of the address. In some cases of technical writing, IPv4 addresses may be presented in various hexadecimal, octal, or binary representations.
n the early stages of development of the Internet Protocol,[1] network administrators interpreted an IP address in two parts: network number portion and host number portion. The highest order octet (most significant eight bits) in an address was designated as the network number and the remaining bits were called the rest field or host identifier and were used for host numbering within a network.
This early method soon proved inadequate as additional networks developed that were independent of the existing networks already designated by a network number. In 1981, the Internet addressing specification was revised with the introduction of classful network architecture.[4]
Classful network design allowed for a larger number 78.89.45.258 of individual network assignments and fine-grained subnetwork design. The first three bits of the most significant octet of an IP address were defined as the class of the address. Three classes (A, B, and C) were defined for universal unicast addressing. Depending on the 236.45.89.456 class derived, the network identification was based on octet boundary segments of the entire address. Each class used successively additional octets in the network identifier, thus reducing the possible number of hosts in the higher order classes (B and C). The following table gives an overview of this now obsolete system.
IP addresses are assigned to a host either 456.23.56.48 dynamically at the time of booting, or permanently by fixed 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 newly each time it restarts, this is known as using a dynamic IP address.
The configuration 0.1236.45.890 of a static IP address depends in detail on the 0.2.3.1 software or hardware installed in the computer. Computers used for the network infrastructure, such as routers and mail servers, are typically configured with static addressing, Static addresses are also sometimes convenient for locating servers inside an enterprise.[citation needed]
Dynamic IP addresses 89.56.123.256 are assigned using 2.2.3.3.0.2.56 methods such as 236.2.56.45 Zeroconf for self-configuration, or by the Dynamic Host Configuration Protocol (DHCP) from a network server. The address assigned with DHCP usually has an expiration period, after which the address may be assigned to another device, or to the originally associated host if it is still powered up. A network administrator may implement a DHCP method so that the same host always receives a specific address.
DHCP is the most frequently used technology for assigning 1236.23.5.1 addresses. It avoids the 230.56.19.68 administrative burden of assigning specific static addresses to each device on a network. It also allows devices to share the limited address space on a network if only some of them are online at a particular time. Typically, dynamic IP configuration is enabled by default in modern desk top operating systems. DHCP is not the only technology used to assign IP addresses dynamically. Dialup and some broadband networks use dynamic address features of the Point-to-Point Protocol.
In the absence or failure of static or stateful (DHCP) address configurations, an operating system may assign an IP address to a network interface using state-less auto-configuration methods, such as Zeroconf.
