IP address: Difference between revisions

{{IPstack}}

An '''IP address''' ('''Internet Protocol address''') is a unique [[address]] that devices use in order to identify and communicate with each other on a [[computer network]] utilizing the [[Internet Protocol]] standard ('''IP''')—in simpler terms, a computer [[address]]. Any participating network device—including [[routers]], [[computer]]s, time-servers, [[Computer printer|printers]], [[Internet]] [[fax]] machines, and some [[telephone]]s—can have their own unique address. Also, many people can find personal information through IP addresses.

An IP address can also be thought of as the equivalent of a [[Address (geography)|street address]] or a [[phone number]] (compare: [[Voice over IP|VoIP]] (voice over (the) internet protocol)) for a computer or other network device on the Internet. Just as each street address and phone number uniquely identifies a building or telephone, an IP address can uniquely identify a specific computer or other network device on a network.

An IP address can appear to be shared by multiple client devices either because they are part of a [[shared hosting]] [[web server]] environment or because a [[proxy server]] (e.g., an [[Internet service provider|ISP]] or [[anonymizer]] service) acts as an [[intermediary]] agent on behalf of its customers, in which case the real originating IP addresses might be hidden from the server receiving a [[request]]. The analogy to telephone systems would be the use of predial numbers (proxy) and extensions (shared).

IP addresses are managed and created by the [[Internet Assigned Numbers Authority]]. IANA generally assigns super-blocks to [[Regional Internet Registry|Regional Internet Registries]], who in turn allocate smaller blocks to [[Internet service provider]]s and [[enterprise]]s.

IP header size is 20 bytes.

==IP versions==

The Internet Protocol has two primary versions in use. Each version has its own definition of an IP address. Because of its prevalence, "IP address" typically refers to those defined by [[IPv4]].

=== IP version 4 ===

{{main|IPv4#Addressing|l1=IPv4 (Addressing)}}

IPv4 uses 32-[[bit]] (4 [[byte]]) addresses, which limits the [[address space]] to 4,294,967,296 (2³²) possible unique addresses. However, many are reserved for special purposes, such as [[private network]]s (~18 million addresses) or [[multicast address]]es (~1 million addresses). This reduces the number of addresses that can be allocated as public Internet addresses, and as the number of addresses available is consumed, an [[IPv4#Exhaustion|IPv4 address shortage ]] appears to be inevitable in the long run. This limitation has helped stimulate the push towards [[IPv6]], which is currently in the early stages of deployment and is currently the only contender to replace IPv4.

Example: 127.0.0.1

=== IP version 5 ===

{{main|IPv5}}

What would be considered ''IPv5'' existed only as an experimental non-IP real time streaming protocol called ST2, described in RFC 1819. In keeping with standard [[UNIX]] release conventions, all odd-numbered versions are considered experimental, and this version was never intended to be implemented, thus not abandoned. [[Integrated services|RSVP]] has replaced it to some degree.

=== IP version 6 ===

{{main|IPv6#Addressing|l1=IPv6 (Addressing)}}(16BYTE)

In IPv6, the new (but not yet widely deployed) standard protocol for the Internet, addresses are 128 bits wide, which, even with a generous assignment of netblocks, will more than suffice for the foreseeable future. In theory, there would be exactly 2¹²⁸, or about 3.403 × 10³⁸ unique host interface addresses. The exact number is:

* 340,282,366,920,938,463,463,374,607,431,768,211,456

This large address space will be sparsely populated, which makes it possible to again encode more routing information into the addresses themselves.

This enormous magnitude of available IPs will be sufficiently large for the indefinite future, even though mobile phones, cars and all types of personal devices are coming to rely on the Internet for everyday purposes.

Example: 2001:0db8:85a3:08d3:1319:8a2e:0370:7334

=== IP version 6 private addresses ===

Just as there are addresses for private, or internal networks in IPv4 (one example being the 192.168.0.1 - 192.168.0.254 range), there are blocks of addresses set aside in IPv6 for private addresses. Addresses starting with FE:80 to FE:FF (or "1111 1110 1" as the first nine bits) are to be used in private networks, and are non-routable.

With IPV6, virtually every device in the world can have an IP address: cars, fridges, lawnmowers and so on. If one's fridge stopped working, for example, a repair specialist could identify the problem without ever visiting in person. It might even be possible to make repairs from abroad, depending on the severity of the problem.

==See also==

*[[Ping]]

*[[IP Multicast]]

*[[MAC address]]

*[[Regional Internet Registry]]

**[[AfriNIC|African Network Information Center]]

**[[American Registry for Internet Numbers]]

**[[RIPE NCC|RIPE Network Coordination Centre]]

**[[Asia-Pacific Network Information Centre]]

**[[Latin American and Caribbean Internet Addresses Registry]]

*[[Subnetwork|Subnet address]]

*[[Geolocation]]

*[[Geolocation software]]

*[[Geo (marketing)]]

*[[Honeypot (computing)|Honeypot]]

*[[Data mining]]

*[[IP address spoofing]]

*[[Help:Page history]]: your IP in the Wikipedia page histories.

*[[Private network]]

==External links==

* {{dmoz|Computers/Internet/Protocols/IP/|IP}}

<!-- Please do not add links for finding out your IP address.

This article is *about* IP addresses, not a newbie guide on how to find yours.

The above DMOZ link should be a good starting point. -->

*[http://www.circleid.com/community/topics/view/IP%20Addressing/ Articles on CircleID about IP addressing]

*[http://www.byte.com/art/9602/sec16/art4.htm IP-Address Management on LANs] &mdash; article in ''[[Byte (magazine)|Byte]]'' magazine

*[http://www.3com.com/other/pdfs/infra/corpinfo/en_US/501302.pdf Understanding IP Addressing: Everything You Ever Wanted To Know]

===RFCs===

* IPv4 addresses: RFC 791, RFC 1519, RFC 1918

* IPv6 addresses: RFC 4291

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[[Category:Internet architecture]]

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