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An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication.〔RFC 760, ''DOD Standard Internet Protocol'' (January 1980)〕 An IP address serves two principal functions: host or network interface identification and location addressing. 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."〔RFC 791, ''Internet Protocol – DARPA Internet Program Protocol Specification'' (September 1981)〕 The designers of the Internet Protocol defined an IP address as a 32-bit number〔 and this system, known as Internet Protocol Version 4 (IPv4), is still in use today. However, because of the growth of the Internet and the predicted depletion of available addresses, a new version of IP (IPv6), using 128 bits for the address, was developed in 1995.〔RFC 1883, ''Internet Protocol, Version 6 (IPv6) Specification'', S. Deering, R. Hinden (December 1995)〕 IPv6 was standardized as RFC 2460 in 1998,〔RFC 2460, ''Internet Protocol, Version 6 (IPv6) Specification'', S. Deering, R. Hinden, The Internet Society (December 1998)〕 and its deployment has been ongoing since the mid-2000s. IP addresses are usually written and displayed in human-readable notations, such as 172.16.254.1 (IPv4), and 2001:db8:0:1234:0:567:8:1 (IPv6). The Internet Assigned Numbers Authority (IANA) manages the IP address space allocations globally and delegates five regional Internet registries (RIRs) to allocate IP address blocks to local Internet registries (Internet service providers) and other entities. ==IP versions== Two versions of the Internet Protocol (IP) are in use: IP Version 4 and IP Version 6. Each version defines an IP address differently. Because of its prevalence, the generic term ''IP address'' typically still refers to the addresses defined by IPv4. The gap in version sequence between IPv4 and IPv6 resulted from the assignment of number 5 to the experimental Internet Stream Protocol in 1979, which however was never referred to as IPv5. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「IP address」の詳細全文を読む スポンサード リンク
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