Learning Objectives

By the end of this chapter, you should be able to:

• Explain why subnetting exists.
• Understand what a subnet is.
• Explain the purpose of a subnet mask.
• Understand CIDR (Classless Inter-Domain Routing) notation.
• Identify network addresses, broadcast addresses, and usable host ranges.
• Calculate the number of hosts available in a subnet.
• Understand how subnetting is used in cloud environments such as AWS.
• Apply subnetting concepts to real-world DevOps scenarios.

Introduction

Imagine a company with 10,000 employees, all working in one massive open office with no walls or departments.

Whenever someone needs to make an announcement, everyone hears it.

As the company grows:

• Noise increases.
• Communication becomes inefficient.
• Productivity decreases.

A better approach is to divide the office into departments:

• Engineering