Fundamentals of IPv4 address

The backbone of internet communication rests upon the principles of IP addressing. In today’s digital age, it’s pivotal to understand these principles, especially when it comes to the prevalent IPv4 (Internet Protocol version 4) addresses. In this article, we will unravel the fundamentals of IPv4 addressing, helping you decode its intricacies.

What is IPv4?

IPv4 stands for “Internet Protocol version 4”. It is the fourth version of the IP, and it underpins a vast majority of web traffic today. Simply put, IPv4 provides an identification and location system for computers on networks and routes traffic across the Internet.

Structure of an IPv4 address

An IPv4 address is a 32-bit number that is typically represented as a series of four decimal numbers separated by periods (dots). Each of these numbers can range from 0 to 255. For instance, “” is a typical IPv4 address.

Breaking it down:

  • 192 is the first octet.
  • 168 is the second octet.
  • 1 is the third octet.
  • 1 is the fourth octet.

This representation is known as “dotted-decimal” notation.

Types of IPv4 addresses

There are different classifications for Internet Protocol version 4 addresses:

  1. Unicast: This refers to a one-to-one transmission, where one source sends data to one specific destination.
  2. Broadcast: In this mode, data sent by a single source is received by all possible destinations in the network.
  3. Multicast: This is a one-to-many or many-to-many transmission, where data is sent to multiple specified destinations.

Address classes

IPv4 addresses are categorized into different classes based on the range:

  • Class A ( to Supports 16 million hosts on each of 128 networks.
  • Class B ( to Supports 65,000 hosts on each of 16,000 networks.
  • Class C ( to Supports 254 hosts on each of 2 million networks.
  • Class D ( to Reserved for multicast groups.
  • Class E ( to Reserved for experimental purposes.

 Private and Public Addresses

IPv4 addresses are also classified as either private or public:

  • Public IP Addresses: These are unique throughout the entire web and are used for external communications. ISPs usually assign them.
  • Private IP Addresses: Used within a local area network (LAN) and are not routable on the public internet. Common private IP ranges include:
  • to
  • to
  • to


With the massive growth of the internet, there arose a need to further segment networks, leading to the concept of subnetting. Subnetting allows for the creation of multiple logical networks within a single Class A, B, or C network.

CIDR (Classless Inter-Domain Routing)

As we neared the exhaustion of IPv4 addresses, CIDR was introduced to improve both the routing scalability and network address allocation. CIDR uses variable-length subnet masking (VLSM) to allow for more granular allocation of IP addresses to networks.


The IPv4 addressing system, with its various classifications and functions, remains central to our current digital world. Despite the emergence of its successor, IPv6, which promises a broader addressing capacity, the importance of understanding the fundamentals of IPv4 cannot be underestimated. Whether you are setting up a network, managing an online platform, or simply diving into the world of digital communications, a solid grasp of IPv4 principles will serve you well.

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