Home Tech & Gear Understanding IPv4 Addressing: Basics and Beyond

Understanding IPv4 Addressing: Basics and Beyond

Understanding IPv4 Addressing: Basics and Beyond
Michel Bakni, CC BY-SA 4.0 via Wikimedia Commons

In the vast landscape of computer networking, understanding the basics of IPv4 addressing is essential. IPv4, or Internet Protocol version 4, is the fourth revision of the Internet Protocol and the foundation of communication over the Internet. In this blog post, we’ll delve into the fundamentals of IPv4 addressing, exploring its structure, purpose, and significance in modern networking.

Basics of IPv4 Addressing

At its core, IPv4 addressing is a method used to uniquely identify devices on a network. An IPv4 address is a 32-bit numerical label expressed in a dotted-decimal format (e.g., Each IPv4 address consists of four octets, with each octet representing 8 bits, resulting in a total of 32 bits.

IPv4 addresses are divided into two main parts: the network portion and the host portion. The network portion identifies the network to which a device belongs, while the host portion identifies the specific device within that network.

IPv4 Address Classes

IPv4 addresses are categorized into different classes, each designed for specific purposes. The classes are denoted by the first few bits of the address, which determine the range of addresses available for networks and hosts. The main classes are:

  • Class A: Addresses start with a 0 bit, allowing for a large number of networks with a smaller number of hosts.
  • Class B: Addresses start with a 10-bit, providing a balance between network and host capacity.
  • Class C: Addresses start with a 110-bit, which is suitable for smaller networks with a larger number of hosts.
  • Class D: Addresses start with an 1110-bit, reserved for multicast communication.
  • Class E: Addresses start with an 1111 bit, which is reserved for experimental purposes and not used for general addressing.

Subnetting and CIDR Notation

Subnetting is often employed to allocate IPv4 addresses efficiently and manage network resources. It involves dividing a single network into smaller sub-networks, each with its own unique network address and host range.

Classless Inter-Domain Routing (CIDR) notation is a method used to represent IP addresses and their associated subnet masks. It allows for more flexible allocation of IP addresses and simplifies the representation of network prefixes. CIDR notation uses a slash followed by a number to denote the number of bits in the network portion of the address (e.g.,

Private and Public IP Addresses

IPv4 addresses can be categorized as either private or public. Private IP addresses are reserved for use within private networks and are not routable over the Internet. They are commonly used for internal communication within an organization or home network. Examples of private IP address ranges include:

  • Class A: to
  • Class B: to
  • Class C: to

Public IP addresses, on the other hand, are globally routable and can be accessed over the Internet. They are assigned by Internet Service Providers (ISPs) and are unique to each device connected to the Internet.


Understanding IPv4 addressing is foundational to any discussion on computer networking. From its basic structure to its application in subnetting and CIDR notation, IPv4 addressing plays a crucial role in the functioning of modern networks. By grasping the fundamentals outlined in this blog post, network administrators and enthusiasts alike can gain a deeper appreciation for the underlying mechanisms that drive communication across the Internet. Check out the possibilities at Prefixbroker.com!

Featured Michel Bakni, CC BY-SA 4.0 via Wikimedia Commons