Dotted Decimal Notation

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What Does Dotted Decimal Notation Mean?

Dotted decimal notation is a system of presenting numbers that is a little different from the common conventions in arithmetic as it is taught in schools. Specifically, dotted decimal notation is used in various IT contexts, including in Internet Protocol addresses.

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Techopedia Explains Dotted Decimal Notation

At its core, dotted decimal notation is just another way of recording and displaying a big number. It is a particular method of notation that can replace “octets” or sets bytes (eight individual bits) in machine language. Dotted decimal notation effectively puts numbers in different containers that are separated by dots or decimals.

In changing a set of bytes into dotted decimal notation, the ones and zeros making up the bite of information are enumerated into decimal-delineated numbers between 0 and 255. In IP version 4 addresses, which are 32 bits long, this results in four numbers, for example: 0.0.172.1

The dotted decimal notation system used so commonly in IP addressing is just one of several choices for representing numbers differently. Another common one is the hexadecimal system, in which traditional numbers are augmented by letters of the alphabet in a base-16 system.

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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.