Learning Objectives

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

• Explain what routing is and why it is necessary.
• Understand how routers forward packets between networks.
• Describe the purpose of routing tables.
• Explain the role of the default gateway.
• Differentiate between static and dynamic routing.
• Follow the path a packet takes from a user's device to a cloud-hosted application.
• Understand how routing works in cloud environments such as AWS.
• Apply routing concepts to real-world DevOps troubleshooting.

Introduction

Imagine you want to travel from your home in Port Harcourt, Nigeria, to an office in Berlin, Germany.

You don't magically appear there.

Instead, your journey follows a planned route:

Home
   ↓
Local Road
   ↓
Highway
   ↓
Airport
   ↓
International Flight
   ↓
Berlin Airport
   ↓
Taxi
   ↓
Office

At every stage, someone decides where you should go next.

Computer networks work in exactly the same way.

When your laptop sends data to a server on another network—or on the other side of the world—the data doesn't travel in one giant leap. Instead, it moves from one network device to another, with each device deciding the next best destination.

This process is called routing.