IP ADDRESS & IP ADDRESS CLASSES

IP Address

• An Internet Protocol (IP) address is a binary number that uniquely identifies computers and other devices on a network. 
• An IP address is a logical address, it can be changed.

 

Versions of IP Address                      

1. Internet Protocol version 4 (IPv4)
2. Internet Protocol version 6 (IPv6)

1. Internet Protocol version 4 (IPv4)

• An IP address consists of 32 bits (0s or 1s).
• The 32 bits of an IP address divided into four 8-bit fields called octets or bytes.  
• Each octet is converted to a decimal number in the range 0-255 and separated by a period (a dot). 

1st Octet/ Byte	2nd Octet/ Byte	3rd Octet/ Byte	4th Octet/ Byte
00000000	00000000	00000000	00000000
11111111	11111111	11111111	11111111

  
Example of an IPv4 Address in Binary and Dotted Decimal Formats

Binary Format	Dotted Decimal Notation
11000000 10101000 00000011 00011000	192.168.3.24

IP Address Classes (IPv4)

• The Internet community originally defined five IP address classes based on the network size.
• It defines the possible number of networks and the number of hosts per network.

 IP Address Classes

C L A S S	First Octet range	IP Address Range	Total Number for This Class of Network	Number of Hosts Per Network
A	1–      126	1.0.0.0 to 126.255.255.255	125	16,777,216
B	128– 191	128.0.0.0 to 191.255.255.255	16,384	65,532
C	192– 223	192.0.0.0 to 233.255.255.255	2,097,152	254
D	224-  239	224.0.0.0 to 239.255.255.255	Multicast Reserved
E	240-  255	240.0.0.0 to 255.255.255.255	Reserved for experimental use

 

The Network ID (also known as a network address) identifies the devices that are located on the same physical network. All devices on the same physical network must have the same network ID.

The host ID (also known as a host address) identifies a computer, printer, server, router, or other host within a network. Each host must be unique address to the network ID.

0.0.0.0 : address is reserved for the default network.  

255.255.255.255 : address is reserved for network broadcast 

127.0.0.0-127.255.255.255 : Loopback address is designated for the software lookback interface of a machine.

Class	Octet / Byte
	1st	2nd	3rd	4th
A	N	H	H	H
B	N	N	H	H
C	N	N	N	H

Types of IP Addresses

A. Public IP Address

An IP address is considered public if the IP number is falls outside any of the IP ranges reserved for the private uses by Internet standards groups. The Internet Assigned Numbers Authority (IANA) controls ownership of these IP ranges and assigns each block to organizations such as Internet Service Providers (ISPs) who in turn allocate individual IP addresses to customers.

B. Private IP Address

An IP address is reserved for private uses by Internet standards groups. These private IP address ranges exist:

Class	First IP in block	Last IP in block
A	10.0.0.0	10.255.255.255
B	172.16.0.0	172.31.255.255
C	192.168.0.0	192.168.255.255

Subnet Mask

• Subnet mask is used to identify numbers of host bit and network bit of an IP address. 
• In Subnet mask 0 indicate host bit and 1 indicate network bit. 

Lists the default subnet masks

C L A S S	Bits for Subnet Mask				Decimal Notation for Subnet Mask
	Octet / Byte				Octet / Byte
	1st	2nd	3rd	4th	1st	2nd	3rd	4th
A	11111111	00000000	00000000	00000000	255	0	0	0
B	11111111	11111111	00000000	00000000	255	255	0	0
C	11111111	11111111	11111111	00000000	255	255	255	0

IP Address Assignment  

A. Static IP Addresses are manually assigned to a computer by an administrator.

B. Dynamic IP Addresses are assigned to the devices that require temporary connectivity to the network. The most common protocol used for assigning dynamic IP address is Dynamic Host Configuration Protocol (DHCP).

Link Local Address or APIPA: When a DHCP server fails to provide IP Address. APIPA allocates IP addresses in the private range 169.254.0.1 to 169.254.255.254. In APIPA, all devices use the default subnet mask 255.255.0.0 and all reside on the same subnet. 
  

2. Internet Protocol version 6 (IPv6) 

• IPv6 addresses are 128 bit long. 
• It uses 32 hexadecimal (0-9 and A-F) numbers to represent an address and is organized into 8 blocks. 
• Each block represents 4 hexadecimal (hex) digits each separated by a colon. 
• A hex digit is represented as a 4 bit binary number.

IPv6 provides the benefits such as increase address space and security improvements:

• It provides secure communication over the Internet.
• It provides a way to change addresses that are assigned to the hosts for maintaining address assignment within a site.
• It provides globally unicast addressing.
• IPv6 address assignment allows easier renumbering, dynamic allocation and recovery of addresses.

Example of an IPv6 Address:

AA00:1234:CCA0:1100:0563:FBCA:9ABC:0056

IPv6 addresses are categories into three different types:

• Unicast addresses assign to a single interface that allow one host to send and receive data. 
• Multicast addresses represents IP addresses for a dynamic group of hosts that send packets to all members of that group.
• Any Cast addresses is created automatically when a unicast address is assigned to more than one interface.

Identify Class of an IP Address:           

IP Address: 100.10.20.16

Step1: Check 1st octet? (Here, It is ‘100’)

Step2: Now check in which class 1st octet  belongs (Here, ‘100’ is from the range of Class A)

Conclusion:   IP: 100.10.20.16 is from Class A