GCSE Computer Science: Networks and Network Security Guide

Network types

A LAN (Local Area Network) covers a small area, like a school or home. A WAN (Wide Area Network) connects devices over a larger area, such as between cities or countries — the internet is the largest WAN.

Network topologies

A star topology connects every device to a central switch, so if one cable fails only that device is affected. A bus topology connects devices along a single shared cable, which is cheaper but a single break can affect the whole network.

Common security threats

Malware (including viruses and ransomware) can damage or lock data. Phishing tricks people into revealing personal information through fake messages. SQL injection can be used to attack poorly secured databases through vulnerable input forms.

Protecting networks

Protection methods include firewalls (filtering network traffic), encryption (scrambling data so it can't be read without a key), strong passwords, and keeping software up to date with security patches.

Common mistakes

• Mixing up LAN and WAN, or star and bus topologies.
• Describing a security threat without explaining how it actually works.
• Assuming one single method (like a firewall) is enough to protect a network on its own.