🛩️Tutorial-01

🌐 Web Development Course -Internet Basics

🛜 How Does the Internet Work?

🔑 Principle 1: Sharing Information

Computer A → Computer B via cable. Signal: 1 = High Voltage, 0 = Low Voltage ✅

🔑 Principle 2: Problem of Scale

100 computers = 4950 cables 😱. Solution → Switch ✅ creates a LAN.

🔑 Principle 3: Connecting Networks

LAN + Router → Connect offices → 🌍 Internet

🔑 Principle 4: Finding Anyone (Addressing)

Every device = IP Address. Example: 142.250.184.142

🔑 Principle 5: Reliability & Fairness

Files split into Packets 📦. Reassembled using TCP/IP.

📍 IP Address

• IPv4 → 32-bit, e.g., 172.217.16.142
• IPv6 → 128-bit, e.g., 2001:0db8:85a3::

🌍 Public vs Private IP

Public = global identity 🌐
Private = local identity 🏠 (e.g., 192.168.x.x)

💻 MAC Address

Unique hardware ID, e.g., 3C:22:FB:A3:B4:C5

🔢 Port Numbers

Ports = 🚪 doors for services

• 0–1023 → Well-known (HTTP 80, HTTPS 443)
• 1024–49151 → Registered (React 3000)
• 49152–65535 → Dynamic (temporary)

🌐 DNS (Domain Name System)

DNS = Internet’s Phonebook 📖. Converts www.google.com → 142.250.72.206

User (www.google.com)
       |
       v
   DNS Resolver
       |
   Root Servers
       |
    TLD (.com)
       |
 Authoritative DNS
       |
   Final IP Found