This tutorial explains the basic concepts of creating subnets in computer networks with examples. Find out what the subnet is and why we do it in computer networks, as well as the pros and cons of the subnet in detail.

What is the subnet?

The subnet is a process of dividing a single large network into several small networks. A single large network is like a city without sector or address. In such a city, a postman can take 3 to 4 days to find a single address. Whereas if the city is divided into sectors and streets, it can easily find any address in less than an hour.

Let’s take another example. Due to maintenance, a power cut is expected. If the city is divided into sectors, the electric service can make a local announcement for the affected sector rather than making an announcement for the whole city.

example of the benefit of subnet 2

Besides these two examples, you can take several other real-life examples where large objects are divided into smaller sections.

Computer networks also follow the same concept. In computer networks, the subnet is used to divide a large IP network into small IP networks called subnets.

A default network of class A, B and C provides respectively 16777214, 65534, 254 hosts. Having as many hosts in the same network always creates several problems such as broadcast, collision, congestion, etc.

Let’s take a simple example. In a company, there are four departments; sales, production, development and management. In each department, there are 50 users. The company used a private Class C IP network. Without any subnet, all the computers will work in one large network.

example of a single network subnet

Computers use broadcast messages to access and provide information about the network. A broadcast message is an announcement message in a computer network which is received by all the hosts on the network.

Earlier in this tutorial, we discussed an example of an electrical advertisement. You can associate this example with this example. In this example, we learned how dividing a city into sectors can reduce the ad area.

In this example, since all computers belong to the same network, they will receive all broadcast messages, regardless of which broadcast messages they receive that are relevant to them or not.

Just as the city is divided into sectors, this network can also be divided into subnets. Once the network is divided into subnets, computers will only receive the programs that belong to them.

Since the company has four departments, it can divide its network into four subnets. The following figure shows the same network after the subnet.

Example of network subnet in subnet

Subnet table
The description Network 1 Network 2 Network 3 Network 4
Network address
able-bodied hosts to to to to
Mailing address

To find out how this table is prepared or how the subnet is made, please see the following parts of this tutorial.

Advantage of the subnet
  • The subnet allows us to break a single large network into smaller networks. Small networks are easy to manage.
  • The subnet reduces network traffic by only allowing broadcast traffic relevant to the subnet.
  • By reducing unnecessary traffic, the subnet improves overall network performance.
  • By blocking traffic from a subnet in a subnet, the subnet increases network security.
  • The subnet reduces the IP range requirement.
Disadvantage of the subnet
  • Different subnets need an intermediary device called a router to communicate with each other.
  • Since each subnet uses its own network address and broadcast address, more subnets mean more wasted IP addresses.
  • Ad complexity subnet in the network. An experienced network administrator is required to manage the network in subnets.

That’s all for this introductory part. In the following sections, we will learn in detail the components and terminology of the subnet. If you have any suggestions or comments about this tutorial, please email me. If you like this tutorial, be sure to share it with your friends via your favorite social channel.


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