What is an IP Address?

An IP (Internet Protocol) address is a numerical label assigned

to the devices connected to a computer network that uses the IP
for communication.

IP address act as an identifier for a specific machine on a

particular network. It also helps you to develop a virtual
connection between a destination and a source. The IP address is
also called IP number or internet address. It helps you to
specify the technical format of the addressing and packets
scheme. Most networks combine TCP with IP.

An IP address consists of four numbers, each number contains one

to three digits, with a single dot (.) separates each number or
set of digits.

Parts of IP address
IP Address is divided into two parts:

 Prefix: The prefix part of IP address identifies the

physical network to which the computer is attached. . Prefix
is also known as a network address.
 Suffix: The suffix part identifies the individual computer
on the network. The suffix is also called the host address.
 Max number
Address Subnet Example Leading
Class of Application
Range masking IP bits
networks
IP
Used for large
Class 1 to 126 255.0.0.0 1.1.1.1 8 128
number of hosts.
A
IP
128 to Used for medium size
Class 255.255.0.0 128.1.1.1 16 16384
191 network.
B
IP
192 to Used for local area
Class 255.255.255.0 192.1.11. 24 2097157
223 network.
C
IP
224 to Reserve for multi-
Class NA NA NA NA
239 tasking.
D
This class is
IP reserved for
240 to
Class NA NA NA NA research and
254
E Development
Purposes.

IP Header Classes:

 How does IP address work?

 IP address works in an IP network like a postal address. For

example, a postal address combines two addresses, address,

or your area your house address.

 The address or your area is a group address of all houses

that belong to a specific area. The house address is the

unique address of your homes in that area. Here, your area

is represented by a PIN code number.

 In this example, the network address comprises all hosts

which belong to a specific network. The host address is the

unique address of a particular host in that network.

 What is Classful Addressing?

 Classful addressing is a network addressing the Internet’s

architecture from 1981 till Classless Inter-Domain Routing

was introduced in 1993.

 This addressing method divides the IP address into five

separate classes based on four address bits.

 Here, classes A, B, C offers addresses for networks of three

distinct network sizes. Class D is only used for multicast,

and class E reserved exclusively for experimental purposes.

 Let’s see each of the network classes in detail:

Class A Network

 This IP address class is used when there are a large number

of hosts. In a Class A type of network, the first 8 bits

(also called the first octet) identify the network, and the

remaining have 24 bits for the host into that network.

 An example of a Class A address is 102.168.212.226. Here,

“102” helps you identify the network and 168.212.226

identify the host.

 Class A addresses 127.0.0.0 to 127.255.255.255 cannot be

used and is reserved for loopback and diagnostic functions.

Class B Network

 In a B class IP address, the binary addresses start with 10.

In this IP address, the class decimal number that can be

between 128 to 191. The number 127 is reserved for loopback,

which is used for internal testing on the local machine. The

first 16 bits (known as two octets) help you identify the

network. The other remaining 16 bits indicate the host

within the network.

 An example of Class B IP address is 168.212.226.204, where

*168 212* identifies the network and *226.204* helps you

identify the Hut network host.

Class C Network

 Class C is a type of IP address that is used for the small

network. In this class, three octets are used to indent the

network. This IP ranges between 192 to 223.

 In this type of network addressing method, the first two

bits are set to be 1, and the third bit is set to 0, which

makes the first 24 bits of the address them and the

remaining bit as the host address. Mostly local area network

used Class C IP address to connect with the network.

 Example for a Class C IP address:

  192.168.178.1

Class D Network

 Class D addresses are only used for multicasting

applications. Class D is never used for regular networking

operations. This class addresses the first three bits set to

“1” and their fourth bit set to use for “0”. Class D

addresses are 32-bit network addresses. All the values

within the range are used to identify multicast groups

uniquely.

 Therefore, there is no requirement to extract the host

address from the IP address, so Class D does not have any

subnet mask.

Example for a Class D IP address:

227.21.6.173

Class E Network

Class E IP address is defined by including the starting four

network address bits as 1, which allows you two to incorporate
addresses from 240.0.0.0 to 255.255.255.255. However, E class is
reserved, and its usage is never defined. Therefore, many network
implementations discard these addresses as undefined or illegal.

Example for a Class E IP address:

243.164.89.28
Limitations of classful IP addressing

Here are the drawbacks/ cons of the classful IP addressing

method:

 Risk of running out of address space soon

 Class boundaries did not encourage efficient allocation of
address space

Rules for assigning Network ID:

The network ID will be assigned based on the below-given rules:

 The network ID cannot start with 127 because 127 belongs to

class A address and is reserved for internal loopback
functions.
 All bits of network ID set to 1 are reserved for use as an
IP broadcast address and cannot be used.
 All bits of network ID are set to 0. They are used to denote
a particular host on the local network and should not be
routed.

Summary:

 An IP (Internet Protocol) address is a numerical label

assigned to the devices connected to a computer network that
uses the IP for communication.
 IP Address is divided into two parts: 1) Prefix 2)Suffix
 IP address works in a network like a postal address. For
example, a postal address combines two addresses, address,
or your area your house address.
 In a class A type of network, the first 8 bits (also called
the first octet) identify the network, and the remaining
have 24 bits for the host into that network.
 In class B type of network, the first 16 bits (known as two
octets) help you identify the network. The other remaining
16 bits indicate the host within the network.
 In class C, three octets are used to indent the network.
This IP ranges between 192 to 223.
 Class D addresses are 32-bit network addresses. All the
values within the range are used to identify multicast
groups uniquely.
 Class E IP address is defined by including the starting four
network address bits as 1.
 The major drawback of IP address classes is the risk of
running out of address space soon.
 Important rule for assigning network id is that the network
ID cannot start with 127 as this number belongs to class A
address and reserved for internal loopback functions.