IPv4 addresses are 32-bit numbers that uniquely identify devices connected to the internet. The total address space consists of over 4 billion possible addresses. Addresses are divided into classes based on the bits in the first octet, with classes A, B, and C used for general IP addressing and classes D and E reserved for other uses. Subnetting allows a single class A or B address to be divided into multiple subnets to create more networks, while supernetting combines multiple class C addresses into a larger supernetwork to create a mid-sized block of addresses.

1. Submited By
Rinku Nahar Hossan
IP Addressing
Classful Addressing (Subnetting &
Supernetting)
IP Address: An IPv4 address is a 32-bit address or 4-bytes that uniquely
and universally defines the connection of a device to the internet.
1.Two devices in the Internet can never have the same address at the same
time.
2. An address may be assigned to a device for a time period and then taken
away and assigned to another device.
Address Space:IPV4 address space is the total number of addresses
used by the protocol.
If a protocol uses N bits to define an address,the address space is 2^n .
IPv4 uses 32-bit address.
The address space=2^32=4,294,967,296 ( more than 4 billion)

2. This means, if there were no restrictions, more than 4 billion devices could be
connected to the Internet.
Notations:There are two types of notations:1.Binary & 2.Dotted Decimal
Binary: 11001100 11100011 00011110 01010101
Dotted Decimal: 204 . 227 . 30 . 85
Classful Addressing: The 32 bit IP address is divided into five sub-
classes. These are:
 Class A
 Class B
 Class C
 Class D
 Class E
Each of these classes has a valid range of IP addresses. Classes D and E are
reserved for multicast and experimental purposes respectively. The order of bits
in the first octet determine the classes of IP address.
IPv4 address is divided into two parts:
 Network ID
 Host ID
The class of IP address is used to determine the bits used for network ID and
host ID and the number of total networks and hosts possible in that particular
class. Each ISP or network administrator assigns IP address to each device that
is connected to its network.

3. Subnetting:If an organization was granted a large block in classes A
or B It could divide the addresses into several contiguous groups and
assign each group to smaller networks( subnets).It increases the number
of 1s in the mask.
Example:Given IP 192.168.10.0 ,requirement usable hosts = 14.Find out
the address class,default mask,Subnet mask,total host,usable host,total
subnet,usable subnet,No of bits borrowed.(Class c)
 Address Class: C
 Default Mask:255.255.255.0
 Subnet Mask:255.255.255.240
 Total Hosts:16
 Usable Hosts:14
 Total Subnets:16
 Usable Subnets:14
 No of Bits Borrowed:4

4. Supernetting:Huge demand for midsize blocks.Although class A and B
addresses are almost depleted,class C addresses are still available( size of
block= 256 so address did not satisfy the needs).In supernetting,an organization
can combine several class C blocks to create a larger range of addresses.Several
networks are combined to create a supernetwork( supernet).
Example: