Feb 08

What is an IP address

 What is an IP address?

  • IP Address provide a way to identify machines on a network
  • IP address is a unique identifier on the network you assigned device.

IP usage

To connect one computer/peripheral to another computer/peripheral, for transferring data to or from another computer or send an e-mail message, you first need to know where the other computer or peripheral is – therefore you need the computer’s “address (an IP Address).”

An IP (Internet Protocol) address is an identifier for a particular machine on a particular network; it is part of a scheme to identify computers on the Internet.

IP addresses are also referred to as doted decimal notation ( and Internet addresses

  • Used to connect to another computer
  • Allows transfers of files and e-mail

IP structure:

An IP address consists of four decimal sections separated by dots (, commonly written in decimal.

  • IP addresses consist of four sections of decimal number e.g. (
  • Each section is 8 bits long in binary e.g.    ( 00001010. 00001010.00000000.00001011)
  • Each section can range from 0 to 255. Here each section bits can be all 1 or all 0 e.g. (00000000.00000000.00000000.00000000) or (11111111.1111111.11111111.11111111)
  • Written, for example,
  • These four sections represent the computer/node itself and the network it is on
  • These four section Network and Host address. The network portion is assigned and the host section is determined by the network administrator.

Network and Host portion in different protocols:

Novel IPX:  Novel has 32bits networks address and 32bits host address fixed.

Apple Talk: Apple talk has 16bits network address and 8 bits host address fixed.

DEC Net: DEC NET has 6 bits network address and 10 bits host address fixed.

IP Address Formats:

IP addresses are separated into five classes. Classes A, B and C are the mostly used the first/starting bits determine IP address class which it belong to and the classes determines by the network and host portion of an IP address.  How much of the address is taken up with the network address and how much with the host address.


Subnetting :

Division of a network into subnets for example, division of a Class B address into a number of Class  C addresses.  Some of the host bits are used for creating subnet bits.

  • Division of local networks
  • Greater number of networks
  • Simplifies addressing