IPv4 – What is it?

IPv4 – What is it?

In the realm of internet technology, there is perhaps no concept more fundamental, yet widely misunderstood, than Internet Protocol version 4 (IPv4). It forms the very foundation of how devices connect and communicate over the internet, yet its core principles are often seen as complex and elusive. Let’s demystify IPv4 and its integral role in our digital world.

What is IPv4?

IPv4, short for Internet Protocol Version 4, is the fourth version of IP, a set of rules that govern the way data is sent and received over the internet. It is the most widely used version, serving as the principal communications protocol in the Internet protocol suite.

A simplified analogy is to think of the internet as a vast global postal service, and IPv4 as the standard for addressing and routing packages (data packets, in this case) between destinations. Without a proper addressing system, the data packages would get lost or misplaced, resulting in communication failures.

The Anatomy of an IPv4 Address

An IPv4 address is composed of 32 bits, and is usually shown as four numbers separated by periods, each ranging from 0 to 255, e.g., This is known as the dotted decimal format.

These addresses are categorized into five classes (A, B, C, D, E) for different types of networks, from small (Class A) to large (Class E). For most home users, a Class C network is used, which supports 254 hosts (devices) on a single network.

The Need for Subnetting and Network Address Translation (NAT)

Given that IPv4 uses 32-bit addresses, theoretically, it can support up to 4.3 billion unique IP addresses. But with the explosive growth of internet-connected devices, we’ve rapidly run out of available addresses. To tackle this issue, two important techniques have been employed: subnetting and Network Address Translation (NAT).

Subnetting allows an IP network to be divided into smaller networks, thereby efficiently using IP addresses. Think of it as dividing a large building into smaller apartments.

On the other hand, NAT allows a single device, such as a router, to act as an agent between the Internet and a local network, meaning all devices behind the router use private IP addresses and the router uses its own public IP address to communicate on the internet.

The Successor: IPv6

While IPv4 has served us admirably since its inception, the need for a new protocol became apparent due to the diminishing pool of available IPv4 addresses. This led to the creation of IPv6, which uses 128-bit addresses, providing an almost infinite number of unique addresses.

While IPv6 is gradually being adopted, it’s not backward compatible with IPv4, leading to a slow transition. Many internet service providers and organizations currently operate in a dual-stack network, supporting both IPv4 and IPv6 simultaneously.


IPv4 is a testament to the foresight of early internet pioneers, serving as the backbone of internet communication for over four decades. Although we’re witnessing a gradual shift to IPv6, understanding IPv4 remains crucial. It continues to coexist with its successor, reminding us of the power of innovation while teaching us lessons on managing finite resources in an expanding digital universe.

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