Data Communication and Security

About this unit

This unit explains how data travels from one device to another and how it is kept safe. It covers the components of data communication, the direction of data flow, switching techniques, bandwidth and data rate, and the wired and wireless media that carry signals. It traces mobile technology from 1G to 5G, introduces the protocols that govern the Internet, and then turns to security threats such as malware and denial of service and the tools used to prevent them.

Key ideas

• Components: sender, receiver, message, communication medium and protocol.
• Simplex, half-duplex and full-duplex communication.
• Circuit switching and packet switching.
• Guided media (twisted pair, coaxial, optical fibre) and unguided media (radio, microwave, infrared, Bluetooth, Wi-Fi).
• Protocols such as HTTP, HTTPS, FTP, IP, PPP, SMTP, POP3 and IMAP.
• Threats: viruses, worms, Trojans, spam, adware, DoS, snooping and eavesdropping.
• Defences: antivirus software, firewalls, safe browsing and HTTPS.

How to prepare

Make short comparison lists: simplex versus duplex, circuit versus packet switching, virus versus worm versus Trojan, HTTP versus HTTPS. Learn one everyday example for each term. Practise simple data-rate calculations (time = data size ÷ data rate).