Internet Protocol version 4 (IPv4) has been the driving force behind the internet’s astronomical growth and the advancement of global communication. As the fourth iteration of the Internet Protocol (IP), IPv4 plays a pivotal role in most network communications. This article explores the fundamental aspects of IPv4, its structure, functions, and limitations, and its co-existence with the newer IPv6.

What is IPv4?

IPv4 is a core protocol for the internet, serving as the principal technology that allows devices to connect and communicate over a network. Essentially, it’s the technology that lets your device send or receive data to or from other devices on the internet.

At its heart, IPv4 is a set of rules that define how data is sent and received over a network. It’s responsible for addressing, routing, and fragmentation of packets, and operates on a best-effort delivery model.

IPv4 Addressing

One of the key concepts in IPv4 is addressing. Every device on an IPv4 network has a unique IP address, which is used to identify the device in the network. Here’s what you need to know about IPv4 addressing:

  • Structure: IPv4 addresses consist of 32 bits, typically represented as four sets of decimal numbers separated by periods (e.g., Each set represents 8 bits (an octet), with values ranging from 0 to 255.
  • Classes: IPv4 addresses are divided into five classes (A, B, C, D, E), based on the first octet of the address. Classes A, B, and C are used for unicast addresses, Class D is used for multicast addresses, and Class E is reserved for future or experimental purposes.
  • Public and Private Addresses: Not all IPv4 addresses can be accessed over the internet. Certain address ranges are reserved for private networks, meaning they can be used for local networking but are not routable on the public internet.

IPv4 Packet Structure

IPv4 communication is built around packets, which are chunks of data sent over a network. An IPv4 packet includes a header and a payload. The header contains information about the packet’s destination, options for routing, and more, while the payload contains the actual data being transferred.

IPv4 and NAT

Network Address Translation (NAT) is a crucial aspect of IPv4 networking. NAT allows multiple devices on a private network to share a single public IP address. This is primarily used to conserve public IPv4 addresses, given their scarcity.

IPv4 Limitations and The Advent of IPv6

The most notable limitation of IPv4 is the exhaustion of address space. With a maximum of approximately 4.3 billion addresses, IPv4 doesn’t have enough addresses for every device currently connected to the internet, let alone future growth.

This address exhaustion led to the development of Internet Protocol version 6 (IPv6), offering a vastly larger address space. However, the transition to IPv6 has been slow, and IPv4 is still widely used due to its deep integration into the internet’s infrastructure.


Despite the emergence of IPv6, IPv4 remains a fundamental protocol in the realm of internet communication. Its enduring significance is a testament to its design and functionality, which have supported the internet’s expansion for over four decades. However, with the continuing growth of the internet and the rise of Internet of Things (IoT) devices, the transition to IPv6 will become increasingly essential.


Public IPv4 addresses are unique across the entire internet, allowing devices to communicate globally. In contrast, private IPv4 addresses are used within local networks and are not routable on the internet. Multiple devices in different private networks can have the same private IPv4 address without causing conflicts.

IPv4 addresses are limited because they consist of only 32 bits, providing approximately 4.3 billion unique addresses. Considering the rapidly growing number of devices connecting to the internet, this pool of addresses has proven insufficient, leading to the development of IPv6.

Yes, a network device can operate with both IPv4 and IPv6 addresses. This dual-stack configuration allows devices to communicate over networks using either protocol, which is particularly useful during the ongoing transition from IPv4 to IPv6.

Network Address Translation (NAT) is a method used to conserve public IPv4 addresses. NAT allows multiple devices on a local network to share a single public IP address. All outbound traffic appears to originate from the shared public address, while inbound responses are correctly routed to the originating device.

While IPv6 adoption is growing, it’s unlikely that IPv4 will become obsolete in the near future. Many networks and devices still rely heavily on IPv4. Transition technologies have been developed to facilitate gradual migration from IPv4 to IPv6, allowing them to coexist for the foreseeable future.

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