The Internet: How It Works
Introduction to the Internet
The Internet is a global network of interconnected computers that communicate using standardized protocols. It enables the sharing of information and resources across the world.
Key Internet Concepts
- Packet-switched network
- Distributed system architecture
- Protocol-based communication
- Client-server model
- IP addressing system
Internet Protocol (IP) Addressing
IPv4 Address Structure
IPv4 addresses are 32-bit numbers divided into four octets, displayed as decimal numbers separated by dots.
| IP Address | Binary Representation | Type |
|---|---|---|
| 192.168.1.1 | 11000000.10101000.00000001.00000001 | Private Network |
| 8.8.8.8 | 00001000.00001000.00001000.00001000 | Public DNS (Google) |
| 127.0.0.1 | 01111111.00000000.00000000.00000001 | Localhost |
IPv6 Addressing
IPv6 uses 128-bit addresses to provide a vastly larger address space, written in hexadecimal format.
Example IPv6: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
Network Protocols
TCP/IP Protocol Suite
| Layer | Protocols | Function |
|---|---|---|
| Application | HTTP, FTP, SMTP, DNS | User-level services |
| Transport | TCP, UDP | End-to-end communication |
| Internet | IP, ICMP | Routing and addressing |
| Network Access | Ethernet, Wi-Fi | Physical transmission |
Common Protocols Explained
- HTTP (Hypertext Transfer Protocol)
- Web page transfer
- Request-response model
- Stateless protocol
- DNS (Domain Name System)
- Domain name resolution
- Hierarchical naming system
- Distributed database
- TCP (Transmission Control Protocol)
- Reliable data delivery
- Connection-oriented
- Flow control
Domain Name System (DNS)
DNS Resolution Process
- User enters domain name (e.g., www.example.com)
- Local DNS cache check
- Query to DNS resolver
- Root server query
- TLD server query
- Authoritative server query
- IP address returned
Domain Name Structure
| Part | Example | Purpose |
|---|---|---|
| Subdomain | www | Service identifier |
| Domain | example | Organization name |
| TLD | com | Type of organization |
Web Technologies
Core Technologies
HTML
Structure and content of web pages
example.html
<html>
<head>
<title>Page Title</title>
</head>
<body>
<h1>Hello World</h1>
</body>
</html>CSS
Styling and layout of web pages
styles.css
body {
background-color: #f0f0f0;
font-family: Arial, sans-serif;
}
h1 {
color: blue;
text-align: center;
}JavaScript
Interactive behavior and functionality
script.js
function greet() {
let name = prompt("Enter your name");
alert("Hello, " + name + "!");
}Network Security
Common Security Threats
Malware
- Viruses
- Trojans
- Ransomware
- Spyware
Network Attacks
- DDoS attacks
- Man-in-the-middle
- Packet sniffing
- Port scanning
Social Engineering
- Phishing
- Pretexting
- Baiting
- Quid pro quo
Security Measures
| Measure | Purpose | Example |
|---|---|---|
| Encryption | Data protection | HTTPS, SSL/TLS |
| Firewalls | Network protection | Packet filtering |
| Authentication | Access control | 2FA, passwords |
| Updates | Vulnerability patching | Security patches |
Internet of Things (IoT)
IoT Components
Sensors
- Temperature
- Motion
- Light
- Humidity
Connectivity
- Wi-Fi
- Bluetooth
- Zigbee
- 5G
Processing
- Edge computing
- Cloud processing
- Data analytics
- AI/ML
IoT Applications
- Smart homes
- Industrial automation
- Healthcare monitoring
- Agricultural systems
- Smart cities
- Transportation
Future of the Internet
Emerging Technologies
5G and Beyond
- Higher speeds
- Lower latency
- More connections
- New applications
Web3
- Decentralization
- Blockchain
- Smart contracts
- Digital assets
AI Integration
- Smart networks
- Automated systems
- Predictive analytics
- Enhanced security