Chapter 1: Subnetting

What is a subnet?

A subnet, or subnetwork, is a network inside a network. Subnets make networks more efficient. Through subnetting, network traffic can travel a shorter distance without passing through unnecessary routers to reach its destination.

What is an IP address?

In order to understand subnets, we must quickly define IP addresses. Every device that connects to the Internet is assigned a unique IP (Internet Protocol) address, enabling data sent over the Internet to reach the right device out of the billions of devices connected to the Internet. While computers read IP addresses as binary code (a series of 1s and 0s), IP addresses are usually written as a series of alphanumeric characters.

What do the different parts of an IP address mean?

This section focuses on IPv4 addresses, which are presented in the form of four decimal numbers separated by periods, like 203.0.113.112. (IPv6 addresses are longer and use letters as well as numbers.)

Every IP address has two parts. The first part indicates which network the address belongs to. The second part specifies the device within that network. However, the length of the "first part" changes depending on the network's class.

Networks are categorized into different classes, labelled A through E. Class A networks can connect millions of devices. Class B networks and Class C networks are progressively smaller in size. (Class D and Class E networks are not commonly used.)

Let's break down how these classes affect IP address construction:

Class A network: Everything before the first period indicates the network, and everything after it specifies the device within that network. Using 203.0.113.112 as an example, the network is indicated by "203" and the device by "0.113.112."

Class B network: Everything before the second period indicates the network. Again using 203.0.113.112 as an example, "203.0" indicates the network and "113.112" indicates the device within that network.

Class C network: For Class C networks, everything before the third period indicates the network. Using the same example, "203.0.113" indicates the Class C network, and "112" indicates the device.

YouTube Video Explaining In More Details: https://www.youtube.com/watch?v=ecCuyq-Wprc

REFERENCES: 

What is a subnet? | How subnetting works | Cloudflare UK. (n.d.). Cloudflare. [online] Available at: https://www.cloudflare.com/en-gb/learning/network-layer/what-is-a-subnet/.[Accessed:27/06/22]

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