IP addressing is a fundamental concept in computer networking, enabling devices to communicate and exchange data over the internet. Subnetting is a technique used to divide an IP network into smaller, manageable segments, allowing for efficient allocation of IP addresses. Although subnetting can seem daunting to beginners, this article aims to demystify the process and make IP addressing and subnetting easy to grasp.

Understanding IP Addresses

An IP address is a unique numerical label assigned to each device connected to a network. It consists of two components: the network portion and the host portion. The network portion identifies the specific network to which the device belongs, while the host portion identifies the individual device within that network.

IP addresses are typically represented in two formats: IPv4 and IPv6. IPv4 addresses consist of four sets of numbers separated by dots (e.g.,, while IPv6 addresses use a hexadecimal format with eight groups of four characters (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).

The Need for Subnetting

As the internet grew, so did the demand for IP addresses. IPv4, the most widely used version of IP addressing, has a limited address space, leading to address exhaustion. Subnetting helps optimize the allocation of IP addresses and reduces wastage by dividing large networks into smaller subnetworks or subnets.

How Subnetting Works

Subnetting involves borrowing bits from the host portion of an IP address to create a subnet mask. The subnet mask determines the size of the subnet and differentiates between the network and host portions. In binary form, the subnet mask consists of consecutive ones followed by consecutive zeros. The ones indicate the network bits, and the zeros indicate the host bits.

For example, a typical subnet mask for a Class C IPv4 address (e.g., is In binary, this is represented as 11111111.11111111.11111111.00000000. Here, the first three octets are reserved for the network, and the last octet is available for host addresses.

Subnetting Example

Let’s take the IP address as an example. The /24 denotes that the first 24 bits are reserved for the network, leaving 8 bits for host addresses (32 – 24 = 8).

With 8 bits for hosts, we have 2^8 (256) possible host addresses in each subnet. However, the first and last addresses in a subnet are reserved, leaving 254 usable host addresses per subnet.

Suppose we want to create four subnets from the original network. To do this, we need to borrow two bits from the host portion, giving us 4 subnets with 62 usable host addresses each.

The new subnet mask becomes (in binary: 11111111.11111111.11111111.11000000). Each subnet now has 62 usable host addresses.

Benefits of Subnetting

Subnetting offers several advantages:

  1. IP Address Conservation: Subnetting allows efficient utilization of IP addresses, delaying the exhaustion of IPv4 addresses.
  2. Improved Network Performance: Smaller subnets reduce broadcast traffic, leading to better network performance and less network congestion.
  3. Enhanced Security: Subnetting enables network administrators to implement security measures and isolate specific subnets, adding an extra layer of protection.


Subnetting plays a crucial role in optimizing IP address allocation and network management. By understanding the fundamentals of IP addressing and subnetting, you can efficiently design and configure networks, ensuring efficient resource utilization and improved network performance.

Remember, subnetting can become more complex in larger networks with different subnetting techniques. However, grasping the basics outlined in this article provides a solid foundation for further exploration.