System Design Crash Course in 4 Hours

How Internet Works?
How API Works?
What is DNS?
What is TCP?
What is TLS?
HTTP vs HTTPS?
What is a Server?
IPv4 vs IPv6 address?
What is a Firewall, Gateway, Load Balancer?
L3 vs L7 Gateway?
L4 vs L7 Load Balancer?

Timeline (API + Internet Explained)
00:00 Precap
03:30 What is API
04:08 What is Client
04:49 What is Server
08:53 What is Database
10:57 API Request and Response Example
14:36 What is DNS
19:18 Find IP Address of Website
20:45 How DNS Works
33:19 Is There Only One DNS
38:09 How Request Reaches Nearest DNS
39:39 How DNS Chooses Server IP
49:14 Who Provides DNS
56:30 Who Pays for DNS
1:04:54 What is TCP and 3-Way Handshake
1:15:43 New TCP for every Request?
1:23:45 What is TLS and Why TLS Handshake
1:31:42 Check TLS Certificate in Browser
1:39:19 API Request Example
1:41:10 Check API Response in Browser
1:45:18 How API Request Travels Over the Internet
1:53:37 IPv4 vs IPv6
1:57:56 Role of Firewall
2:00:45 Role of Gateway
2:07:54 Role of Load Balancer
2:16:58 Gateway vs Load Balancer
2:27:34 Are Firewall, Gateway, and Load Balancer Servers
2:30:06 Who Provides Firewall, Gateway, and Load Balancer
2:31:30 API System Diagram
2:41:59 L3 Gateway vs L7 Gateway
2:45:03 L4 Load Balancer vs L7 Load Balancer
2:46:12 Complete API Flow End to End
2:49:41 How Gateway Routes Requests to Microservices
2:56:28 How Responses Are Sent Back to Client
3:27:13 Summary – How API and Internet Work

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How API Works | Client Server Architecture Explained | DNS, TCP, TLS, Gateway, Load Balancer, Firewall | Internet Basics

Ever wondered how the Internet really works behind the scenes?
In this detailed video, I’ll explain everything from Client-Server Communication, API Requests, DNS resolution, TCP & TLS handshakes, to Load Balancer, Gateway, and Firewall architecture — in the simplest way possible.

By the end of this video, you’ll clearly understand how an API request travels across the internet — from your browser to the backend server — and how different components like DNS, TCP, TLS, Gateway, and Load Balancer make it secure and reliable.

📘 Topics Covered:

What is API, Client, Server, and Database

How DNS Works & Finds IP Address

TCP 3-Way Handshake Explained

TLS & HTTPS Security

Role of Firewall, Gateway & Load Balancer

L3, L4, and L7 Gateways & Load Balancers

Complete API Flow from Request to Response

💡 Perfect for beginners preparing for System Design, Backend Development, or Network Fundamentals.

🔔 Subscribe for more videos on System Design, DSA, and Software Engineering concepts explained in simple Hindi!

#API #SystemDesign #InternetWorking #BackendDevelopment #NetworkingBasics #TechEducation

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