1.2 Network Math  
  1.2.7 Four-octet dotted decimal representation of 32-bit binary numbers  
Currently, addresses assigned to computers on the Internet are 32-bit binary numbers. To make it easier to work with these addresses, the 32-bit binary number is broken into a series of decimal numbers. To do this, split the binary number into four groups of eight binary digits. Then convert each group of eight bits, also known as an octet into its decimal equivalent. Do this conversion exactly as was shown in the binary-to-decimal conversion topic on the previous page.

When written, the complete binary number is represented as four groups of decimal digits separated by periods. This is referred to as dotted decimal notation and provides a compact, easy to remember way of referring to the 32 bit addresses. This representation is used frequently later in this course, so it is necessary to understand it. When converting to binary from dotted decimal, remember that each group, which consists of one to three decimal digits represents a group of eight binary digits. If the decimal number that is being converted is less than 128, zeros will be needed to be added to the left of the equivalent binary number until there are a total of eight bits.

Example:

Convert 200.114.6.51 to its 32-bit binary equivalent.

Convert 10000000 01011101 00001111 10101010 to its dotted decimal equivalent.

 

Web Links

IP Addressing Architecture

http://www2.rad.com/networks/1994/ ip_addr/tcpip2.htm