Networks and the Internet

1. What is a Network?

A network is a group of two or more computers or devices connected together to share data, resources, and information.

Purpose of a Network

• Sharing files and data
• Sharing hardware (printers, scanners)
• Communication (email, messaging)
• Accessing shared software and storage

2. Types of Networks

a) LAN (Local Area Network)

• Covers a small area like a home, school, or office.
• High speed and low cost.

b) WAN (Wide Area Network)

• Covers large geographical areas (cities, countries).
• The Internet is the largest WAN.

c) MAN (Metropolitan Area Network)

• Covers a city or large campus.

d) PAN (Personal Area Network)

• Very small network around one person (Bluetooth, hotspot).

3. Network Topologies

The arrangement of devices in a network.

• Bus Topology – Single cable; simple but prone to failures.
• Star Topology – Devices connected to a central hub; most common.
• Ring Topology – Devices connected in a circle.
• Mesh Topology – Each device connected to many others; very reliable.

4. Network Devices

• Router – Connects different networks and directs data.
• Switch – Connects devices within a LAN.
• Modem – Converts digital signals to be transferred over phone lines or cables.
• Access Point – Provides wireless (Wi-Fi) connectivity.
• Firewall – Protects network from unauthorized access.

5. What is the Internet?

The Internet is a global network of interconnected computers that communicate using standard protocols. It allows access to services like the World Wide Web (websites), email, cloud storage, and more.

How the Internet Works

• Data travels in small units called packets.
• Packets move across different networks using IP (Internet Protocol).
• TCP (Transmission Control Protocol) ensures reliable delivery.

This combined system is known as TCP/IP.

6. IP Address

A unique number assigned to each device connected to the internet.

Types

• IPv4 – Older format (e.g., 192.168.0.1).
• IPv6 – Newer format to support more devices.

7. DNS (Domain Name System)

DNS translates website names into IP addresses. Example: "google.com" → 142.250.190.78

8. Cyber Security Concerns in Networks and Internet

• Unauthorized access
• Data interception (sniffing)
• DDoS attacks
• Man-in-the-middle attacks
• Malware spreading through networks

Protection Measures

• Use firewalls
• Encrypt data
• Secure Wi-Fi with strong passwords
• Update network devices
• Use VPN for safe browsing

9. Importance in Cyber Security

Understanding networks and the internet is essential because:

• Most cyber attacks occur over networks.
• Securing networks means securing data.
• Helps cybersecurity professionals detect, prevent, and respond to threats.