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An IP address (or Internet Protocol address) is a unique address that certain electronic 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, switches, computers, infrastructure servers (e.g., NTP, DNS, DHCP, SNMP, etc.), printers, Internet fax machines, and some telephones—can have its own IP address that is unique within the scope of the specific network. Some IP addresses are intended to be unique within the scope of the global Internet, while others need to be unique only within the scope of an enterprise. The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... In computer networking, the term network address may refer to one of the following: A network layer address, i. ... A computer network is an interconnected group of computers. ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... [[Image:Link title]] // [[Image:Media:Example. ... This article is about a computer networking device. ... For other uses, see Switch (disambiguation). ... This article is about the machine. ... The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. ... The Domain Name System (DNS) associates various sorts of information with domain names; most importantly, it serves as the phone book for the Internet by translating human-readable computer hostnames, e. ... DHCP redirects here. ... The Simple Network Management Protocol (SNMP) forms part of the internet protocol suite as defined by the Internet Engineering Task Force (IETF). ... A computer printer, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper or transparencies. ... For other uses, see Fax (disambiguation). ... For other uses, see Telephone (disambiguation). ...

The IP address acts as a locator for one IP device to find another and interact with it. It is not intended, however, to act as an identifier that always uniquely identifies a particular device. In current practice, an IP address is not always a unique identifier due to technologies such as dynamic assignment and network address translation. This page is a candidate for speedy deletion. ... In computer networking, Network Address Translation (NAT, also known as Network Masquerading, Native Address Translation or IP Masquerading) is a technique of transceiving network traffic through a router that involves re-writing the source and/or destination IP addresses and usually also the TCP/UDP port numbers of IP packets...

On the public Internet as opposed to private internets or intranets, IP addresses are managed and created by the Internet Assigned Numbers Authority (IANA). The IANA generally allocates super-blocks to Regional Internet Registries, who in turn allocate smaller blocks to Internet service providers and enterprises. The Internet Assigned Numbers Authority (IANA) is the entity that oversees global IP address allocation, DNS root zone management, and other Internet protocol assignments. ... A Regional Internet Registry (RIR) is an organisation overseeing the allocation and registration of Internet number resources within a particular region of the world. ... “ISP” redirects here. ... Enterprise storage is the field of information technology focused on the storage, protection, and retrieval of data in large-scale environments. ...

IP versions

The Internet Protocol (IP) has two versions currently in use (see IP version history for details). Each version has its own definition of an IP address. Because of its prevalence, "IP address" typically refers to those defined by IPv4. The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... Internet Protocol version 4 (IPv4) is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. ...

An illustration of an IP address (version 4), in both dot-decimal notation and binary.

Image File history File links Ipv4_address. ... Image File history File links Ipv4_address. ... Dot-decimal notation is a method of expressing octets using base-10 rather than hexadecimal. ... The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ...

IP version 4 addresses

Main article: IPv4#Addressing

IPv4 only 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 networks (~18 million addresses) or multicast addresses (~270 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 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. Internet Protocol version 4 (IPv4) is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. ... This article is about the unit of information. ... For other users of the word/name byte, see byte (disambiguation). ... In computing, an address space defines a range of discrete addresses, each of which may correspond to a physical or virtual memory register, a network host, peripheral device, disk sector or other logical or physical entity. ... // In Internet terminology, a private network is a network that uses private IP address space, following the agreed standard of RFC 1918. ... In computer networking a multicast address is an identifier for a group of hosts that have joined a multicast group. ... Internet Protocol version 4 (IPv4) is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. ... Internet Protocol version 6 (IPv6) is a network layer for packet-switched internetworks. ...

IPv4 addresses are usually represented in dotted-decimal notation (four numbers, each ranging from 0 to 255, separated by dots, e.g. 147.132.42.18). Each range from 0 to 255 can be represented by 8 bits, and is therefore called an octet. It is possible, although less common, to write IPv4 addresses in binary or hexadecimal. When converting, each octet is treated as a separate number. (So 255.255.0.0 in dot-decimal would be FF.FF.00.00 in hexadecimal.) Dot-decimal notation is a method of expressing octets using base-10 rather than hexadecimal. ... In computing, an octet is a grouping of eight bits. ... The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... In mathematics and computer science, hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0–9 and A–F, or a–f. ...

IPv4 address networks

Main article: Subnetwork

Currently, three classes of networks are commonly used. These classes may be segregated by the number of octets used to identify a single network, and also by the range of numbers used by the first octet. A graphic representation of relationships and source of the various variables representing a chunk of C subnets In computer networks, a subnetwork or subnet is a range of logical addresses within the address space that is assigned to an organization. ... Classful networking is the name given to the first round of changes to the structure of the IP address in IPv4. ...

• Class A networks (the largest) are identified by the first octet, which ranges from 0 to 127. Within the class A networks, the 0 network is reserved by IANA and 127 is reserved for the loopback network.
• Class B networks are identified by the first two octets, the first of which ranges from 128 to 191.
• Class C networks (the smallest) are identified by the first three octets, the first of which ranges from 192 to 223.

Some first-octet values have special meanings:

• First octet 127 represents the local computer, regardless of what network it is really in. This is useful when testing internal operations.
• First octet 224 and above are reserved for special purposes such as multicasting.

Octets 0 and 255 are not acceptable values in some situations, but 0 can be used as the second and/or third octet (e.g. 10.2.0.100). Multicast is sometimes also (incorrectly) used to refer to a multiplexed broadcast. ...

A class A network does not necessarily consist of 16 million machines on a single network, which would excessively burden most network technologies and their administrators. Instead, a large company is assigned a class A network, and segregates it further into smaller sub-nets using Classless Inter-Domain Routing. However, the class labels are still commonly used as broad descriptors. Warning! This Article contains disinformation. ...

IPv4 private addresses

Main article: Private network

Machines not connected to the outside world (e.g. factory machines that communicate with each other via TCP/IP) need not have globally-unique IP addresses. Three ranges of IPv4 addresses for private networks, one per class, were standardized by RFC 1918; these addresses will not be routed, and thus need not be coordinated with any IP address registrars. // In Internet terminology, a private network is a network that uses private IP address space, following the agreed standard of RFC 1918. ... // In Internet terminology, a private network is a network that uses private IP address space, following the agreed standard of RFC 1918. ...

Each block is not necessarily one single network, although it is possible. Typically the network administrator will divide a block into subnets; for example, many home routers automatically use a default address range of 192.168.0.0 - 192.168.0.255 (192.168.0.0/24). A graphic representation of relationships and source of the various variables representing a chunk of C subnets In computer networks, a subnetwork or subnet is a range of logical addresses within the address space that is assigned to an organization. ... A residential gateway is a hardware device connecting a home network with a wide area network (WAN) or the Internet. ...

An illustration of an IP address (version 6), in hexadecimal and binary.

Image File history File links Ipv6_address. ... Image File history File links Ipv6_address. ... In mathematics and computer science, hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0–9 and A–F, or a–f. ... Look up binary in Wiktionary, the free dictionary. ...

IP version 6 addresses

Main article: IPv6#Addressing

IPv6 is a new standard protocol intended to replace IPv4 for the Internet. Addresses are 128 bits (16 bytes) 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. Further, this large address space will be sparsely populated, which makes it possible to again encode more routing information into the addresses themselves. Internet Protocol version 6 (IPv6) is a network layer for packet-switched internetworks. ... BITS may have any of the following meanings: In computer science, bits are binary digits, which may each have the value one or zero. ... This article refers to the unit of binary information. ...

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

Writing for Technology Review in 2004, Simson Garfinkel wrote that there will exist "roughly 5,000 addresses for every square micrometer of the Earth's surface".^[1] This enormous magnitude of available IP addresses 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. Technology Review is an innovation and technology magazine affiliated with the Massachusetts Institute of Technology. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ...

The above source, however, involves a common misperception about the IPv6 architecture. Its large address space is not intended to provide unique addresses for every possible point. Rather, the addressing architecture is such that it allows large blocks to be assigned for specific purposes and, where appropriate, aggregated for providing routing. With a large address space, there is not the need to have complex address conservation methods as used in classless inter-domain routing (CIDR). Warning! This Article contains disinformation. ...

Windows Vista, Apple Computer's Mac OS X, all modern Linux distributions^[2], and an increasing range of other operating systems include native support for the protocol, but it is not yet widely deployed elsewhere. Windows Vista (pronounced ) is a line of operating systems developed by Microsoft for use on personal computers, including home and business desktops, laptops, Tablet PCs, and media centers. ... Apple Inc. ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... A Linux distribution (also called GNU/Linux distribution) is a member of the Linux family of Unix-like software distributions. ...

IPv6 private addresses

Just as there are addresses for private, or internal networks in IPv4 (one example being the 192.168.0.0 - 192.168.255.255 range), there are blocks of addresses set aside in IPv6 for private addresses. Addresses starting with FE80: are called link-local addresses and are routable only on your local link area. This means that if several hosts connect to each other through a hub or switch then they would communicate through their link-local IPv6 address.

Early designs specified an address range used for "private" addressing, with prefix FEC0. These are called site-local addresses (SLA) and are routable within a particular site, analogously to IPv4 private addresses. Site-local addresses, however, have been deprecated by the IETF since they create the same problem that does the existing IPv4 private address space (RFC 1918). With that private address space, when two sites need to communicate, they may have duplicate addresses that "combine". In the IPv6 architecture, the preferred method is to have unique addresses in a range not routable on the Internet, issued to organizations (e.g., enterprises).

The preferred alternative to site-local addresses are centrally assigned unique local unicast addresses (ULA). In current proposals, they will start with the prefix FC00.

Neither ULA nor SLA nor link-local address ranges are routable over the internet.

IP address subnetting

Main article: Subnetwork

Both IPv4 and IPv6 addresses utilize subnetting, or dividing the IP address into two parts: the network address and the host address. By using a subnet mask, the computer can determine where to split the IP address. A graphic representation of relationships and source of the various variables representing a chunk of C subnets In computer networks, a subnetwork or subnet is a range of logical addresses within the address space that is assigned to an organization. ... A graphic representation of relationships and source of the various variables representing a chunk of C subnets In computer networks, a subnetwork or subnet is a range of logical addresses within the address space that is assigned to an organization. ... A graphic representation of relationships and source of the various variables representing a chunk of C subnets In computer networks, a subnetwork or subnet is a range of logical addresses within the address space that is assigned to an organization. ...

As an alternative to the subnet mask, CIDR notation can also be used. In CIDR notation, the IP address is followed by a slash and the number of bits used to designate the subnetwork. For example, a typical IP address and its subnet mask may look like 192.0.2.1 and 255.255.255.0, respectively. The CIDR notation for the same IP address and subnet would be 192.0.2.1/24, because the first 24 bits of the IP address indicate the subnetwork. Classless Inter-Domain Routing (CIDR), introduced starting in 1993, is the latest refinement to the way IP addresses are interpreted. ... A graphic representation of relationships and source of the various variables representing a chunk of C subnets In computer networks, a subnetwork or subnet is a range of logical addresses within the address space that is assigned to an organization. ...

Static and dynamic IP addresses

When a computer is manually configured to use the same IP address each time it connects, this is known as a Static IP address. In contrast, in situations when the computer's IP address is assigned automatically, it is known as a Dynamic IP address.

Method of assignment

Static IP addresses are manually assigned to a computer by an administrator. The exact procedure varies according to platform. This contrasts with dynamic IP addresses, which are assigned either randomly (by the computer itself, as in Zeroconf), or arbitrarily assigned by a server using Dynamic Host Configuration Protocol (DHCP). Even though IP addresses assigned using DHCP may stay the same for long periods of time, they can generally change. In some cases, a network administrator may implement dynamically assigned static IP addresses. In this case, a DHCP server is used, but it is specifically configured to always assign the same IP address to a particular computer, and never to assign that IP address to another computer. This allows static IP addresses to be configured in one place, without having to specifically configure each computer on the network in a different way. Zeroconf or Zero Configuration Networking is a set of techniques that automatically create a usable IP network without configuration or special servers. ... DHCP redirects here. ...

In the absence of both an administrator (to assign a static IP address) and a DHCP server, the operating system may still assign itself a dynamic IP address using Zeroconf. These IP addresses are known as link-local addresses. For IPv4, link-local addresses are in the 169.254.0.0/16 address range. Zeroconf or Zero Configuration Networking is a set of techniques that automatically create a usable IP network without configuration or special servers. ...

Uses of dynamic addressing

Dynamic IP Addresses are most frequently assigned on LANs and broadband networks by Dynamic Host Configuration Protocol (DHCP) servers. They are used because it avoids the administrative burden of assigning specific static addresses to each device on a network. It also allows many devices to share limited address space on a network if only some of them will be online at a particular time. In most current desktop operating systems, dynamic IP configuration is enabled by default so that a user does not need to manually enter any settings to connect to a network with a DHCP server. DHCP is not the only technology used to assigning dynamic IP addresses. Dialup and some broadband networks use dynamic address features of the Point-to-Point Protocol. DHCP redirects here. ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ...

Uses of static addressing

Static addressing is essential in some infrastructure situations, such as finding the Domain Name Service directory host that will translate domain names to numbers (IP addresses). Static addresses are also convenient, but not absolutely necessary, to locate servers inside an enterprise. An address obtained from a DNS server comes with a time to live, or caching time, after which it should be looked up to confirm that it has not changed. Even static IP addresses do change as a result of network administration, however (RFC 2072). The Domain Name System or DNS is a system that stores information about host names and domain names in a kind of distributed database on networks, such as the Internet. ... The Domain Name System (DNS) associates various sorts of information with domain names; most importantly, it serves as the phone book for the Internet by translating human-readable computer hostnames, e. ... Time to live (sometimes abbreviated TTL) is a limit on the period of time or number of iterations or transmissions in computer and computer network technology that a unit of data (e. ... The Domain Name System (DNS) associates various sorts of information with domain names; most importantly, it serves as the phone book for the Internet by translating human-readable computer hostnames, e. ...

Modifications to IP addressing

IP blocking and firewalls

Main articles: IP blocking and Firewall

Firewalls are common on today's Internet. For increased network security, they allow or deny access to their private network based on the public IP of the client. Whether using a blacklist or a whitelist, the IP address that is blocked is the perceived public IP address of the client, meaning that if the client is using a proxy server or NAT, blocking one IP address might block many individual people. IP blocking is the banning, by a website, mailserver, or other Internet server, of outside connections from certain IP addresses or ranges of them, the intention of this being to keep out people who are judged as hostile or undesirable. ... Firewall may refer to: Firewall (construction), a physical barrier inside a building or vehicle, designed to limit the spread of fire, heat and structural collapse Firewall (networking), a logical barrier designed to prevent unauthorized or unwanted communications between sections of a computer network Firewall (film), a 2006 action film written... Firewall may refer to: Firewall (construction), a physical barrier inside a building or vehicle, designed to limit the spread of fire, heat and structural collapse Firewall (networking), a logical barrier designed to prevent unauthorized or unwanted communications between sections of a computer network Firewall (film), a 2006 action film written... // In Internet terminology, a private network is a network that uses private IP address space, following the agreed standard of RFC 1918. ... Look up whitelist in Wiktionary, the free dictionary. ... In computer networks, a proxy server is a server (a computer system or an application program) which services the requests of its clients by forwarding requests to other servers. ... In computer networking, Network Address Translation (NAT, also known as Network Masquerading, Native Address Translation or IP Masquerading) is a technique of transceiving network traffic through a router that involves re-writing the source and/or destination IP addresses and usually also the TCP/UDP port numbers of IP packets...

IP address translation

Main article: Network Address Translation

IP addresses can appear to be shared by multiple client devices either because they are part of a shared hosting web server environment or because an IPv4 network address translator (NAT) or proxy server 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. A common practice is to have a NAT hide a large number of IP addresses in a private network. Only the "outside" interface(s) of the NAT need to have Internet-routable addresses^[3]. In computer networking, Network Address Translation (NAT, also known as Network Masquerading, Native Address Translation or IP Masquerading) is a technique of transceiving network traffic through a router that involves re-writing the source and/or destination IP addresses and usually also the TCP/UDP port numbers of IP packets... Shared hosting is a form of web hosting where more than one web site is hosted on the same server. ... The inside/front of a Dell PowerEdge web server The term Web server can mean one of two things: A computer program that is responsible for accepting HTTP requests from clients, which are known as Web browsers, and serving them HTTP responses along with optional data contents, which usually are... In computer networking, Network Address Translation (NAT, also known as Network Masquerading, Native Address Translation or IP Masquerading) is a technique of transceiving network traffic through a router that involves re-writing the source and/or destination IP addresses and usually also the TCP/UDP port numbers of IP packets... In computer networks, a proxy server is a server (a computer system or an application program) which services the requests of its clients by forwarding requests to other servers. ... An intermediary is a third party that offers intermediation services between two trading parties. ... Ask can be used to refer: Amplitude-shift keying a telecommuncations term Ask and Embla about Norse Mythology Ask Jeeves A song by The Smiths. ... // In Internet terminology, a private network is a network that uses private IP address space, following the agreed standard of RFC 1918. ...

Most commonly, the NAT device maps TCP or UDP port numbers on the outside to individual private addresses on the inside. Just as there may be site-specific extensions on a telephone number, the port numbers are site-specific extensions to an IP address.

In small home networks, NAT functions are usually performed by a residential gateway device, typically one marketed as a "router". In this scenario, the computers connected to the router would have 'private' IP addresses and the router would have a 'public' address to communicate with the Internet. This type of router allows several computers to share one public IP address. A residential gateway is a hardware device connecting a home network with a wide area network (WAN) or the Internet. ...

See also

Classful networking is the name given to the first round of changes to the structure of the IP address in IPv4. ... Country IP database provides allocated IP raw data from Regional Internet Registries. ... Data mining is the process of sorting through large amounts of data and picking out relevant information. ... In marketing, geo (also called marketing geography) is a discipline within marketing analysis which uses geolocation (geographic information) in the process of planning and implementation of marketing activities. ... Geolocation refers to identifying the real-world geographic location of an Internet connected computer, mobile device, or website visitor. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... It has been suggested that Honeynet be merged into this article or section. ... In computer networking, the term Internet Protocol address spoofing is the creation of IP packets with a forged (spoofed) source IP address. ... IP blocking is the banning, by a website, mailserver, or other Internet server, of outside connections from certain IP addresses or ranges of them, the intention of this being to keep out people who are judged as hostile or undesirable. ... IP Multicast is a method of forwarding IP datagrams to a group of interested receivers. ... As of January 2006, some /8 (formerly Class A) large blocks of IP addresses assigned to single organizations or related groups of organizations, either by the Internet Corporation for Assigned Names and Numbers (ICANN), through the Internet Assigned Numbers Authority[1] or a regional Internet registry, include: Note that this... In computer networking a Media Access Control address (MAC address) or Ethernet Hardware Address (EHA) or hardware address or adapter address is a quasi-unique identifier attached to most network adapters (NICs). ... For other uses, see Ping (disambiguation). ... // In Internet terminology, a private network is a network that uses private IP address space, following the agreed standard of RFC 1918. ... Provider Independent Address Space (PI-addresses) are Internet Protocol addresses assigned by the Registries directly to an end-user organization, without going through an Internet Service Provider. ... A Regional Internet Registry (RIR) is an organisation overseeing the allocation and registration of Internet number resources within a particular region of the world. ... AfriNIC is the Regional Internet Registry (RIR) for Africa. ... The American Registry for Internet Numbers (ARIN) is the Regional Internet Registry (RIR) for Canada, the United States, and portions of the Caribbean. ... The office building that houses APNIC in Brisbane, Australia. ... The Latin American and Caribbean Internet Addresses Registry (LACNIC) is the Regional Internet Registry for Latin America and the Caribbean. ... The Réseaux IP Européens Network Coordination Centre (RIPE NCC) is the Regional Internet Registry (RIR) for Europe, the Middle East and Central Asia. ... A graphic representation of relationships and source of the various variables representing a chunk of C subnets In computer networks, a subnetwork or subnet is a range of logical addresses within the address space that is assigned to an organization. ... A virtual IP address (VIP or VIPA) is an IP address that is not connected to a specific computer or network interface card (NIC) on a computer. ...

References

• Comer, Douglas (2000). Internetworking with TCP/IP:Principles, Protocols, and Architectures --4th ed.. Upper Saddle River, NJ: Prentice Hall. ISBN 0-13-018380-6. 

is the 7th day of the year in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 316th day of the year (317th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Common Era (or Anno Domini), in accordance with the Gregorian calendar. ... is the 157th day of the year (158th in leap years) in the Gregorian calendar. ...

External links

• IP at the Open Directory Project which includes sites that let you find your IP address
• Articles on CircleID about IP addressing
• IP-Address Management on LANs — article in Byte magazine
• Understanding IP Addressing: Everything You Ever Wanted To Know
• How to get a static IP address - clear instructions for all the major platforms
• Internet IP Address Allocation by Country 2008 Report

The Open Directory Project (ODP), also known as dmoz (from , its original domain name), is a multilingual open content directory of World Wide Web links owned by Netscape that is constructed and maintained by a community of volunteer editors. ... Byte magazine was an influential microcomputer magazine in the late 1970s and throughout the 1980s, because of its wide-ranging editorial coverage. ...

RFCs

• IPv4 addresses: RFC 791, RFC 1519, RFC 1918, RFC 2071, RFC 2072
• IPv6 addresses: RFC 4291, RFC 4192