How the Internet Works

Introduction

1970s: No standard method for networks to communicate
Inventors: Vint Cerf and Bob Bobcon created the internetworking protocol, laying the groundwork for the internet

Definition: The internet is a network of networks linking billions of devices globally
Connection Process:
- Devices (e.g., laptops, phones) connect through Wi-Fi
- Wi-Fi connects to an Internet Service Provider (ISP)
- ISP connects to billions of devices via hundreds of thousands of interconnected networks

Design Philosophy: The internet's core is a design philosophy and architecture expressed in protocols
Protocol: A set of rules and standards for communication
Adaptability: Internet’s design allows it to incorporate new communication technologies

Unique Addresses: Each internet-connected device has a unique address (IP address)
IP Addresses: Similar to mailing addresses, essential for sending/receiving data
Internet Protocol (IP): Fundamental protocol for internet communication
- IP Address Structure:
  - Organized in a hierarchy (country, region, subnetwork, device)
  - Represented in bits (traditional IP addresses are 32 bits long)
- IPv4: 32-bit addresses, allowing over 4 billion unique addresses
- IPv6: 128-bit addresses, allowing over 340 undecillion unique addresses
- Transition: Ongoing switch from IPv4 to IPv6

Function: Associates domain names with IP addresses
Process:
- User requests a website by name (e.g., www.code.org)
- System looks up the corresponding IP address via DNS
DNS Servers: Distributed hierarchy, divided into zones (e.g., .org, .com, .net)

DNS Openness: Originally open for government/educational use, vulnerable to cyber attacks
DNS Spoofing: Attackers change DNS data to redirect users to fake websites

Scalability: Both DNS and IP are designed to scale with internet growth
Resilience: Adaptability and structured protocols ensure continued functionality