The Internet’s Phonebook: What is DNS?

So far, we've talked about "Servers" and "Databases" and "Load Balancers."

But there is one fundamental question we skipped.

When you type www.google.com into your browser, how does your computer know where Google is?

The Internet doesn't understand names like "Google," "Facebook," or "LinkedIn." Computers only speak one language: Numbers (IP Addresses). 🌐 Like 142.250.190.46.

Imagine if you had to memorize a string of numbers for every website you visited. "Hey, check out my article at 104.244.42.1!" It would be impossible. 😵‍💫

We need a translator. We need a way to say: "Human speaks: google.com -> Computer understands: 142.250.190.46."

Enter... DNS (Domain Name System). 📡

Think of DNS as the Contacts App on your phone. When you want to call your "Mom," you don't type her phone number. You just tap "Mom." Your phone looks at its contacts list, finds the number associated with "Mom," and dials it.

Here is what happens when you type a URL:

You type: www.swiggy.com Your computer asks the DNS Server: "Hey, where is Swiggy?" The DNS Server looks it up: "Ah, that is at IP address 13.232.12.45." Your computer connects: It uses that IP address to find the Load Balancer we talked about earlier. Without DNS, the internet would just be a messy phonebook of numbers that nobody wants to use.

System Design Foundation #1: DNS is the bridge between how humans think (Names) and how computers connect (IPs).

Next up: Now that we've found the computer (via DNS), how do we actually "talk" to it? We need a common language.

Quick Question: If your Contacts app (DNS) deleted your friend's number, could you still call them? Only if you memorized the number! 👀 Have you ever memorized an IP address? (I haven't!)

Let me know in the comments!