Friday 24 July 2015

IP Addressing

What is an IP address ?

An Internet Protocol Address (IP address) is a numerical label assigned to each device (eg: computer, printer ) participating in a computer network that uses the Internet Protocol (I'll Cover it later) for communication.
In short : Just remember an IP address is given to every device on a network for communication purpose as address tells us where is the device.

An IP address is a software address, not a hardware address (Hardware address is hard coded on the Network Interface Card(NIC). )

IP terminology

Bit: A Bit is one digit, either a 0 or 1.
Byte: A Byte is 7 or 8 bits depending on whether parity is used. I'll use byte as 8 bits in my explanation.
Octet: An Octet, made up of 8 bits, an ordinary 8 bit binary number.

IP addresses are of two types :
IPv4 and IPv6
As for now we will stick to IPv4.
IP address (IPv4) consists of 32 bits of information, divided into four sections referred to as octet or bytes, with each containing 1 byte (8 bits). It can be represented in one of the following three ways:
  • Dotted-Decimal :- To make the IP addresses more easier to read, Internet addresses are usually written in decimal format (dot) seperating the bytes 
       Eg: 192.168.10.1
  • Binary :- In binary notation IP address is represented in 32 bits, i.e. 4 octets. So it is common to hear it as 4 byte address or 32 bit address. 
       Eg: 11000000.10101000.00001010.00000001
Computer Networking, Dotted decimal to binary IP address
NOTE: Since each byte is 8 bits each number in dotted decimal format in an IP address is a number ranging from 0 to 255.
  • Hexadecimal :- An example :- C0.A8.0A.01. It will be discussed in more detail with IPv6
This is a structured or a hierarchical addressing scheme, it can handle a large number of addresses, nearly 4.3 billion (2^32 or 4294967296 ).
This hierarchical scheme has an advantage, if all addresses were unique it would have made efficient routing impossible.
So, instead of treating whole IP address as a unique identifier they are divided into classes.


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