IP Addresses - Versions, Classes & Types

Submitted by Karthikeyan on

​IP Address - Internet Protocol Address

- A numerical address assigned to each device in a computer network.

1. Versions of IP Address

Internet Protocol Version 4 (IPv4)

  • 32 bit number
  • 4 octets
  • Limitation : 4294967296 (232) addresses
  • It is described in RFC 761  September 1981
  • commonly in use today
  • e.g.

Internet Protocol Version 6 (IPv6)

  • 128 bit number
  • 16 octets
  • Limitation : (21283.403×1038 addresses
  • It was developed in 1995 and standardized as rfc2460 in 1998.
  • Not yet widely used.
  • e.g. 2001:0:9d38:90d7:2c0f:19de:4b28:afba

2. Classes of IP Addresses

IPv4 Classes:

Class  A  B  C  D  E

1st Octet Range

1-126* 128-191 192-223 224-239 240-254
IP Addresses Range to to to to to
Default Subnet Mask NA NA
 Network / Host ID N.H.H.H N.N.H.H N.N.N.H NA NA
Number of Networks configurable 126 (27 – 2) 16,382 (214 – 2) 2,097,150 (221 – 2) NA NA
Number of devices configurable per network 16,777,214 (224 – 2) 65,534 (216 – 2) 254 (28 – 2) NA NA
Purpose Large networks Medium sized networks Small networks Reserved for multi casting For research and development


  • Class A - range to - reserved for loop back and diagnostic purposes.
  • Any server / system localhost ip address is


3. Types of IP Addresses

Public vs Private IP Addresses

Public IP address is assigned to a computer by the ISP when it is connected to the Internet.

Private IP addresses are used to configure the devices in a private network (LAN / MAN / WAN). 

For example all the branches of a bank network can be configured using private IP addresses.

All the systems in a LAN can share the same internet connection., i.e, their public IP address will be the same, but the private IP address will differ. 

Reserved IP Range for configuring devices LAN (Private IP Addresses):


Private Networks

Subnet Mask

Address Range

A -

B - -

C -


Static vs Dynamic IP Addresses


  • Static IP address does not change once it is assigned to a device / computer in a network.
  • Since, the IP is static and known there is more possibility for network attacks
  • Used by Web Servers, E-mail Servers
  • Number of allocatable IP addresses is limited in IPv4.Hence, nowadays it is not possible to connect all the devices that exists in world to Internet simultaneously by using IPv4. 


  • Dynamic IP addresses are assigned by ISP using DHCP
  • ​Available IP address is assigned to a device when it is connected to the network, after the session expiry the IP address released for other device's use.
  • Effective use of IP addresses is an advantage of Dynamic IP address assigning.
  • Since, the IP address changes frequently, it become not traceable.