Dot-decimal notation

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Dot-decimal notation is a presentation format for numerical data. It consists of a string of decimal numbers, using the full stop (dot) as a separation character. [1]

Contents

A common use of dot-decimal notation is in information technology where it is a method of writing numbers in octet-grouped base-10 (decimal) numbers. [2] In computer networking, Internet Protocol Version 4 (IPv4) addresses are commonly written using the quad-dotted notation of four decimal integers, ranging from 0 to 255 each. [3]

IPv4 address

An IP address (version 4) in both dot-decimal notation and binary code IPv4 address structure and writing systems-en.svg
An IP address (version 4) in both dot-decimal notation and binary code

In computer networking, the notation is associated with the specific use of quad-dotted notation to represent IPv4 addresses [4] and used as a synonym for dotted-quad notation. [5] Dot-decimal notation is a presentation format for numerical data expressed as a string of decimal numbers each separated by a full stop. For example, the hexadecimal number 0xFF000000 may be expressed in dot-decimal notation as 255.0.0.0.

An IPv4 address has 32 bits. For purposes of representation, the bits may be divided into four octets written in decimal numbers, ranging from 0 to 255, concatenated as a character string with full stop delimiters between each number. [3] This octet-grouped dotted-decimal format may more specifically be called "dotted octet" format, [6] or a "dotted quad address". [7]

For example, the address of the loopback interface, usually assigned the host name localhost, is 127.0.0.1. It consists of the four octets, written in binary notation: 01111111, 00000000, 00000000, and 00000001. The 32-bit number is represented in hexadecimal notation as 0x7F000001.

No formal specification of this textual IP address representation exists. [6] The first mention of this format in RFC documents was in RFC 780 for the Mail Transfer Protocol published May 1981, in which the IP address was supposed to be enclosed in brackets or represented as a 32-bit decimal integer prefixed by a pound sign. A table in RFC 790 (Assigned Numbers) used the dotted decimal format, zero-padding each number to three digits. [6] RFC 1123 (Requirements for Internet Hosts – Application and Support) of October 1989 mentions a requirement for host software to accept “IP address in dotted-decimal ("#.#.#.#") form”, although it notes “[t]his last requirement is not intended to specify the complete syntactic form for entering a dotted-decimal host number”. [8] An IETF draft intended to define textual representation of IP addresses expired without further activity. [6]

A popular implementation of IP networking, originating in 4.2BSD, contains a function inet_aton() for converting IP addresses in character string representation to internal binary storage. In addition to the basic four-decimals format and 32-bit numbers, it also supported intermediate syntax forms of octet.24bits (e.g. 10.1234567; for Class A addresses) and octet.octet.16bits (e.g. 172.16.12345; for Class B addresses). It also allowed the numbers to be written in hexadecimal and octal representations, by prefixing them with 0x and 0, respectively. These features continue to be supported in some software, even though they are considered as non-standard. [6] This means addresses with a component written with a leading zero digit may be interpreted differently in programs that do or do not recognize such formats. [9]

A POSIX-conforming variant of inet_aton, the inet_pton() function, supports only the four-decimal variant of IP addresses. [10]

IP addresses in dot-decimal notation are also presented in CIDR notation, in which the IP address is suffixed with a slash and a number, used to specify the length of the associated routing prefix. For example, 127.0.0.1/8 specifies that the IP address has an eight-bit routing prefix, and therefore the subnet mask 255.0.0.0.

OIDs

Object identifiers use a style of dot-decimal notation to represent an arbitrarily deep hierarchy of objects identified by decimal numbers. They may also use textual words separated by dots, like some computer languages (see inheritance).

Version numbers

Software releases are often given version numbers in dot-decimal notation, with the first digit designating major revisions and the smaller ones progressively more minor releases. Version numbers with a leading zero, say "0.1.8", conventionally indicate that the software is still in beta and does not yet have complete features.

Libraries

Libraries use notation systems consisting of decimal numbers separated by dots, such as the older Dewey Decimal Classification and the Universal Decimal Classification, to classify books and other works by subject. The UDC additionally codes works with multiple dot-decimal topics, separated by colons. [11]

Texts

Dot-decimal notation is often used for sections within a large text. This was standardized in ISO 2145.

Medicine

Toe bones or phalanges of the foot.

   Distal phalanges of the foot
   Middle phalanges of the foot
   Proximal phalanges of the foot

Dot-decimal notation is also used to describe illnesses in a language-neutral way. For instance, the AO Foundation/Orthopaedic Trauma Association (AO/OTA) classification generates numeric codes for describing broken toes. [12] They run 88[meaning a fracture of the phalanges].[number-code of toe, with the big toe=1 and the little toe=5].[number-code of phalanx, counting 1-3 outwards from the foot].[number-code of location on the bone, with 1 being the inner end, 3 the outer, and 2 in-between]. [12] So, for instance, 88.5.3.2 means a fracture to the little toe's outermost bone, in the center. [12] There are other classifications for other fractures and dislocations. [13]

See also

Related Research Articles

In mathematics and computing, the hexadecimal numeral system is a positional numeral system that represents numbers using a radix (base) of sixteen. Unlike the decimal system representing numbers using ten symbols, hexadecimal uses sixteen distinct symbols, most often the symbols "0"–"9" to represent values 0 to 9, and "A"–"F" to represent values from ten to fifteen.

An Internet Protocol address is a numerical label such as 192.0.2.1 that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface identification, and location addressing.

<span class="mw-page-title-main">Internet Protocol version 4</span> Fourth version of the Internet Protocol

Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version deployed for production on SATNET in 1982 and on the ARPANET in January 1983. It is still used to route most Internet traffic today, even with the ongoing deployment of Internet Protocol version 6 (IPv6), its successor.

<span class="mw-page-title-main">IPv6</span> Version 6 of the Internet Protocol

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, and was intended to replace IPv4. In December 1998, IPv6 became a Draft Standard for the IETF, which subsequently ratified it as an Internet Standard on 14 July 2017.

The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.

A MAC address is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking technologies, including Ethernet, Wi-Fi, and Bluetooth. Within the Open Systems Interconnection (OSI) network model, MAC addresses are used in the medium access control protocol sublayer of the data link layer. As typically represented, MAC addresses are recognizable as six groups of two hexadecimal digits, separated by hyphens, colons, or without a separator.

In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages to other hosts on an Internet Protocol (IP) network. Within an IP network, UDP does not require prior communication to set up communication channels or data paths.

Classless Inter-Domain Routing is a method for allocating IP addresses for IP routing. The Internet Engineering Task Force introduced CIDR in 1993 to replace the previous classful network addressing architecture on the Internet. Its goal was to slow the growth of routing tables on routers across the Internet, and to help slow the rapid exhaustion of IPv4 addresses.

A multicast address is a logical identifier for a group of hosts in a computer network that are available to process datagrams or frames intended to be multicast for a designated network service. Multicast addressing can be used in the link layer, such as Ethernet multicast, and at the internet layer for Internet Protocol Version 4 (IPv4) or Version 6 (IPv6) multicast.

Open Shortest Path First (OSPF) is a routing protocol for Internet Protocol (IP) networks. It uses a link state routing (LSR) algorithm and falls into the group of interior gateway protocols (IGPs), operating within a single autonomous system (AS).

<span class="mw-page-title-main">Subnet</span> Logical subdivision of an IP network

A subnetwork or subnet is a logical subdivision of an IP network. The practice of dividing a network into two or more networks is called subnetting.

<span class="mw-page-title-main">Classful network</span> Early system for organizing the IPv4 address space

A classful network is an obsolete network addressing architecture used in the Internet from 1981 until the introduction of Classless Inter-Domain Routing (CIDR) in 1993. The method divides the IP address space for Internet Protocol version 4 (IPv4) into five address classes based on the leading four address bits. Classes A, B, and C provide unicast addresses for networks of three different network sizes. Class D is for multicast networking and the class E address range is reserved for future or experimental purposes.

An organizationally unique identifier (OUI) is a 24-bit number that uniquely identifies a vendor, manufacturer, or other organization.

In computer networking, Teredo is a transition technology that gives full IPv6 connectivity for IPv6-capable hosts that are on the IPv4 Internet but have no native connection to an IPv6 network. Unlike similar protocols such as 6to4, it can perform its function even from behind network address translation (NAT) devices such as home routers.

In computer networks, a reverse DNS lookup or reverse DNS resolution (rDNS) is the querying technique of the Domain Name System (DNS) to determine the domain name associated with an IP address – the reverse of the usual "forward" DNS lookup of an IP address from a domain name. The process of reverse resolving of an IP address uses PTR records. rDNS involves searching domain name registry and registrar tables. The reverse DNS database of the Internet is rooted in the .arpa top-level domain.

The octet is a unit of digital information in computing and telecommunications that consists of eight bits. The term is often used when the term byte might be ambiguous, as the byte has historically been used for storage units of a variety of sizes.

The Internet checksum, also called the IPv4 header checksum is a checksum used in version 4 of the Internet Protocol (IPv4) to detect corruption in the header of IPv4 packets. It is carried in the IP packet header, and represents the 16-bit result of summation of the header words.

A Request for Comments (RFC), in the context of Internet governance, is a type of publication from the Internet Engineering Task Force (IETF) and the Internet Society (ISOC), usually describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.

<span class="mw-page-title-main">IPv6 address</span> Label to identify a network interface of a computer or other network node

An Internet Protocol Version 6 address is a numeric label that is used to identify and locate a network interface of a computer or a network node participating in a computer network using IPv6. IP addresses are included in the packet header to indicate the source and the destination of each packet. The IP address of the destination is used to make decisions about routing IP packets to other networks.

An IPv6 packet is the smallest message entity exchanged using Internet Protocol version 6 (IPv6). Packets consist of control information for addressing and routing and a payload of user data. The control information in IPv6 packets is subdivided into a mandatory fixed header and optional extension headers. The payload of an IPv6 packet is typically a datagram or segment of the higher-level transport layer protocol, but may be data for an internet layer or link layer instead.

References

  1. ↑ "Gepunktete Dezimalschreibweise". Techplugged (in German).
  2. ↑ "What is Dotted Decimal Notation? - Definition from Techopedia". Techopedia.com.
  3. 1 2 "IPv4 and IPv6 address formats". www.ibm.com. An IPv4 address has the following format: x . x . x . x where x is called an octet and must be a decimal value between 0 and 255. Octets are separated by periods. An IPv4 address must contain three periods and four octets. The following examples are valid IPv4 addresses:
    1 . 2 . 3 . 4
    01 . 102 . 103 . 104
  4. ↑ "Dot address". TechTarget. Retrieved 2010-11-18.
  5. ↑ "Dotted Decimal Notation". encyclopedia.com.[ permanent dead link ]
  6. 1 2 3 4 5 Main, Andrew (23 February 2005). Textual Representation of IPv4 and IPv6 Addresses. IETF. I-D draft-main-ipaddr-text-rep-02.
  7. ↑ "Definition of dot address". PCMAG.
  8. ↑ Braden, Robert (1 October 1989). Requirements for Internet Hosts -- Application and Support. IETF. sec. 2.1.
  9. ↑ "Ping and FTP resolve IP address with leading zero as octal". Microsoft Support. Archived from the original on 2006-12-06.
  10. ↑ inet_pton(3)  –  Linux Library Functions Manual
  11. ↑ Taylor, Arlene G. (2005). "15: Decimal Classification". Introduction to Cataloging and Classification (PDF) (10th ed.). preprint, to be published by Libraries Unlimited in2006.
  12. 1 2 3 Godoy-Santos, AL; Giordano, V; Cesar, C; Sposeto, RB; Bitar, RC; Wajnsztejn, A; Sakaki, MH; Fernandes, TD (November 2020). "Hallux Proximal Phalanx Fracture in Adults: An Overlooked Diagnosis". Acta Ortopedica Brasileira. 28 (6): 318–322. doi:10.1590/1413-785220202806236612. PMC   7723381 . PMID   33328790.
  13. ↑ Meinberg, EG; Agel, J; Roberts, CS; Karam, MD; Kellam, JF (January 2018). "Fracture and Dislocation Classification Compendium-2018". Journal of Orthopaedic Trauma. 32 Suppl 1: S1–S170. doi:10.1097/BOT.0000000000001063. PMID   29256945. S2CID   39138324.
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