Learning Objectives

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

• Explain what the Domain Name System (DNS) is and why it exists.
• Understand the relationship between domain names and IP addresses.
• Describe the hierarchical structure of DNS.
• Explain the roles of ICANN, domain registrars, and authoritative DNS servers.
• Understand the DNS resolution process step by step.
• Identify the most common DNS record types.
• Use Linux tools such as nslookup, dig, and host to troubleshoot DNS issues.
• Apply DNS concepts in cloud platforms like AWS and Kubernetes.

Introduction

Imagine trying to call your best friend.

You probably don't memorize their phone number—you simply search for their name in your contacts.

Your phone translates the name into the phone number behind the scenes.

The Internet works in exactly the same way.

Humans prefer names like:

google.com
amazon.com
github.com
openai.com

Computers, however, communicate using IP addresses such as:

142.250.190.78
140.82.114.4
104.18.33.45