ZIMFundi
Sign inJoin free

Topic 7 of 8 · Form 5

Networks, communication and security

Switches, routers, gateways, wireless access points, modems; transmission media (twisted pair, fibre, wireless).

Notes for this topic 1 file, in order

Create a free account to download PDFs.

  1. PDFNetworks, communication and security – Computer Science notes (ZIMSEC A Level)47.3 KB

Network models

  • Client–server and peer-to-peer networks.
  • Topologies: star, bus, mesh; LAN, WAN.
  • The TCP/IP stack: application (HTTP, HTTPS, FTP, SMTP, POP3/IMAP, DNS), transport (TCP – reliable; UDP – fast), internet (IP addressing and routing), link layers.
  • Packet switching versus circuit switching.
  • IPv4 (32-bit) and IPv6 (128-bit) addresses; subnetting; public and private IPs; DHCP; NAT.

Hardware

Switches, routers, gateways, wireless access points, modems; transmission media (twisted pair, fibre, wireless).

Security threats

Malware, phishing, pharming, denial-of-service attacks, hacking, SQL injection and social engineering.

Security measures

Firewalls, proxy servers, encryption, digital certificates and signatures, access rights, authentication (passwords, biometrics, two-factor), antivirus, and regular updates.

Encryption

  • Symmetric encryption: one shared key – fast, but the key must be shared securely.
  • Asymmetric (public key) encryption: a public key encrypts and a private key decrypts. Digital signatures use the sender's private key and verification with their public key.
  • SSL/TLS secures web traffic (HTTPS).

Legal and ethical issues

Data protection (Zimbabwe's Cyber and Data Protection Act, 2021), computer misuse, copyright and software licensing (open source vs proprietary), and the digital divide.

Exam tip: For asymmetric encryption, state clearly which key is used to encrypt and which to decrypt.

Check yourself

  1. Give one difference between TCP and UDP.
  2. How many bits are in an IPv6 address?
  3. How is a digital signature created and verified?
Show answers
  1. TCP is connection-oriented and reliable (acknowledgements, resending); UDP is connectionless and faster with no guarantee of delivery.
  2. 128 bits.
  3. A hash of the message is encrypted with the sender's private key; the receiver decrypts it with the sender's public key and compares hashes.
Next topicBoolean algebra and logic circuits

Questions about this topic (0)

No questions about this topic yet.