Understanding DNS: How Names Become Numbers

Lesson 3: Understanding DNS

The Problem DNS Solves

Humans prefer names. Computers prefer numbers.

You remember:

google.com

But computers need something like:

142.250.195.14

DNS exists to solve this mismatch.

What Is DNS?

DNS (Domain Name System) is like the phonebook of the internet.

It translates:

  • Website names → IP addresses

So when you type a URL, DNS tells your browser:

“This name lives at this number.”

Step-by-Step: How DNS Works

Let’s follow what happens when you type a website name.

Step 1: Browser Checks Its Memory

First, your browser checks:

  • “Have I visited this site before?”
  • “Do I already know its IP address?”

If yes → it skips DNS and loads faster.

If no → it asks for help.

Step 2: Asking the DNS Resolver

Your browser asks a DNS resolver
(usually run by your ISP or a public service like Google DNS).

“Do you know the IP address for this website?”

Step 3: Asking the Internet

If the resolver doesn’t know, it asks other DNS servers in order:

  1. Root servers – “Who handles this domain?”
  2. TLD servers – “Who manages .com, .org, etc.?”
  3. Authoritative server – “Here is the exact IP address.”

This sounds long, but it happens very fast.

Step 4: Returning the Answer

The IP address is sent back to:

  • The resolver
  • Then your browser

Your browser can now contact the correct server.

Why DNS Is So Important

Without DNS:

  • You would need to memorize numbers
  • Websites would be hard to use
  • The internet would feel broken

DNS makes the internet human-friendly.

Common DNS Problems

When DNS fails:

  • Websites don’t load
  • You see errors like “DNS server not responding”

The website may be fine —
but your browser can’t find it.

Reflection Question

Think about this:

If DNS is slow or broken, what happens to the rest of the internet steps you learned earlier?

Lesson Summary

  • DNS translates names into IP addresses
  • It acts like the internet’s phonebook
  • Browsers use DNS before contacting servers
  • DNS problems can stop websites from loading

➡️ Next Lesson: HTTP & HTTPS — How Data Is Sent Safely