18 September 2011

IP Address

IP - Internet Protocol  Address

Every system connected to the Internet or connected to a particular network has
a unique Internet Protocol Address of an IP Address. Just as in the real world
every person has his or her own Home Contact Address, similarly every system
connected to the Internet has its own unique IP Address. Your IP Address is the
address to which data should be sent to ensure that it reaches your system. The
IP Address of a system acts as the system’s unique identity on the net.

‘….Like in the real world everyone has got an individual Home Address or
telephone number so that, that particular individual can be contacted on that
number or address, similarly all computers connected to the Internet are given a
unique Internet Protocol or IP address which can be used to contact that
particular computer…..’

An Ip Address Can be Assigned to
1. Computer
2. printer
3. Ip Phone

U Cannot provide Ip Address to any device which is connected to A Computer on the network.
For Ex:
We Have Two Printers 1 is connected to one of the computer and other is directly connected to the network using LAN Cable.
So U cannot provide Ip Address to The Printer which is connected to the computer.

 Internet Address (IP Address) is a 32-bit address or number, which is
normally written as four decimal numbers (of 8 bits each) , each separated from
the other by a decimal.. This standard is known as the dotted-decimal notation.

Now as u all no It Is used in decimal format Which is divided into 4 parts. Each part is Called An Octet.



Each octet Consists of a number between 0-255 .

IPV6 Is also launched. It Is 128 Bit Address and used in Hexa-decimal Format.

n Total we have 2 to the power 32 ( 4,294,967,296 ) possible unique addresses But Still its too less for the growing world of computers,
 so we are shifting to IPV6.
IPV6 is a 128 bit address so u can calculate yourself what is 2 to the power 128.

Ip address is divided into Further two parts 1. network And Second host

To Communicate between two computers The network part of Both The Pc Must be The same and the host part must be different.

For ex

on 1st PC U gave Ip address network.host.host.host
on 2nd PC U gave ip address Network.Network.Host.Host

They will not communicate because on 1st PC 1st octet is network and rest 3 are host and on the second PC 1st two octets are network and rest two are host.

So to differentiate between network And Host part Ip Address is further Classified between 5 classes

As u know we can use ip address from 0-255
Addresses being used are divided into a number of ranges, which are as follows:

                           Class                                           Range
                                A                    to

                                B                    to
                                C                    to

                                D                    to

                                E                     to

let us refer to the following:

                Class                                      Information
                  A                                           It has the first
8-Bits for Netid and the last 24-bits for Hostid
                  B                                           It has the first
16-Bits for Netid and the last 16-bits for Hostid
                  C                                           It has the first
24-Bits for Netid and the last 8-bits for Hostid
                  D                                           It represents a
32-bit multicast Group ID.
                  E                                            Currently not
being used.

The above table will be clearer after reading the following examples:


An IP Address belonging to Class A means that the network ID is 203
and the host ID is 45.12.34

If the Same IP Address belonged to Class B, then the network ID would become
203.45 and the host ID would become 12.34

And if it belonged to Class C then the network ID would become 203.45.12 and the
host ID would become 34.

Almost all ISP’s prefer to use a Class B Network. If that is the case then each
time you login to your ISP, then the first 2 octets of your IP Address would not
change, while the last two are likely to change. However, even if only the last
octet changes, and the remaining three remain constant, it is likely that the
ISP uses Class B addressing. (Subnetting comes in. Explained later in the

Important Notes
Note 1: is a class A network,
but is reserved for use as a loopback address
Loopback testing means to test weather your Lan card is working or not and Weather TCP/Ip Service is installed or not. Just go to run and type ping 127.x.x.x -t. U can use any number between 0-255 in place of 'x'

Note 2: The network is reserved for use as the default route.

Note 3: Class D addresses are used by groups of hosts or routers
that share a common characteristic. ( Used for multicast )

Note 4: Class E addresses exist (240-248),
but are reserved for future use or Use For testing purpose

Some More Notes About Ip Address Classes
The following are the classes of IP addresses.

*Class A "The first octet denotes the network address, and the last three octets are the host portion.
 Any IP address whose first octet is between 1 and 126 is a Class A address.
 Note that 0 is reserved as a part of the default address, and 127 is reserved for internal loopback testing.

*Class B "The first two octets denote the network address, and the last two octets are the host portion.
Any address whose first octet is in the range 128 to 191 is a Class B address.

*Class C "The first three octets denote the network address, and the last octet is the host portion.
The first octet range of 192 to 223 is a Class C address.

*Class D "Used for multicast. Multicast IP addresses have their first octets in the range 224 to 239.

*Class E "Reserved for future use and includes the range of addresses with a first octet from 240 to 255