CS IB Computer Science Lecture: Topic 3 - Networks

Introduction

• Focus on networks in the IB Computer Science Curriculum
• Useful for learning or revising for exams

Core Concepts

Server and Client

• Server: Central system where data is held
  • Example: Airline check-in kiosk at an airport
• Client: Requests service or connects to server
  • Example: Bar and bartender analogy

Computer Network

• Multiple computers connected, sending/receiving data
• Two types:
  • Centralized (client-server)
  • Peer-to-peer

Network Devices

Hub

• Sends data to all devices on a network
• Less efficient

Switch

• Directs data to specific devices
• More efficient than a hub

Router

• Connects multiple networks
• Example: Home network accessing the internet

The Internet and World Wide Web

• Internet: Physical infrastructure (cables, radio waves)
• World Wide Web: The collection of web pages
• ISPs: Provide internet access and connect through internet exchanges

Data Transmission

Packet Switching

• Data divided into packets
• Packets travel different routes, reassembled at destination

Routers

• Manage packet traffic efficiently
• Provide security

Types of Networks

Local Area Network (LAN)

• Small geographical area
• Higher data transfer rate

Wide Area Network (WAN)

• Larger geographical area
• Connects multiple LANs

Virtual Local Area Network (VLAN)

• Software-based network configurations
• Provides flexibility in network management

Storage Area Network (SAN)

• Dedicated to storage devices
• Fault-tolerant, high performance

Wireless Local Area Network (WLAN)

• Uses Wi-Fi
• Advantages: No cables, global standards
• Disadvantages: Interference, limited range

Personal Area Network (PAN)

• Connects devices in immediate area
• Examples: Bluetooth, Wi-Fi hotspots

Intranet and Extranet

• Intranet: Private network using internet technology
• Extranet: Intranet accessible via an online portal

Virtual Private Network (VPN)

• Secure connection through encrypted tunnel to VPN server
• Provides anonymity and security

Peer-to-Peer Network

• Direct connection between computers
• No centralized server

Protocols

• Rules for data transmission
• Examples: HTTP, SFTP
• Functions: Data integrity, flow control, prevent deadlock

Transmission Media

Wired vs Wireless

• Wired: Ethernet, copper, fiber optic
• Wireless: Wi-Fi, radio waves
• Factors: Security, reliability, cost, speed

Factors Affecting Transmission Speed

• Traffic, time of day, distance, infrastructure
• Environmental, financial, and data type considerations

Compression

• Lossy: Removes data, irreversible
• Lossless: Retains data, reversible

Network Security

Authentication

• One-factor: Passwords
• Two-factor: Password + device
• Three-factor: Password + device + biometric

Encryption

• Encodes data for secure transmission

Media Access Control (MAC)

• Controls network access using unique device addresses

Firewalls

• Analyze incoming/outgoing data packets

Physical Security

• Locked doors, cages, secure rooms

Conclusion

• Comprehensive overview of networks for IB exam preparation
• Slides provide detailed diagrams and additional explanations