1.3 How Systems Communicate
Explain network infrastructure and data transmission, then assess cybersecurity and personal-privacy risks and safeguards.
How to study WJEC GCSE Computer Science
Learn the computing principle, apply it to the named system or scenario, trace the data and control flow, and test the result against requirements.
Core concepts
Concept 1
Topologies; routers, hubs, switches, bridges, gateways and WAPs; TCP/IP, HTTP(S), FTP, SMTP, POP3, IMAP, BGP, DNS, packets and routing
Exam cue: Identify the current WJEC unit, the command word and whether the task asks for knowledge, application or computational analysis.
Concept 2
Malware, social engineering, brute-force variants, denial of service, interception, keylogging, session hijacking, spoofing and SQL injection
Exam cue: Identify the asset, threat, vulnerability and consequence before selecting layered technical and human controls.
Concept 3
Penetration testing, network forensics, anti-malware, access control, MFA, secure by design, encryption, backups and privacy
Exam cue: Use precise terminology, trace inputs and state changes, and test the answer against the data, scenario or program behaviour.
Risk pitfalls and guardrails
Naming a security control without explaining which threat it mitigates, how it works or what residual risk remains.
Guardrail: Avoid generic descriptions, unchecked traces and cross-board assumptions; make every answer depend on the named data, system, algorithm or scenario.
Importing the legacy WJEC structure, a different board's content or a Foundation/Higher tier assumption.
Guardrail: Use qualification code 3460QS or 3460CS and the current two-unit untiered structure; do not import a legacy or cross-board route.
Giving a generic description without applying it to the named system, data set, algorithm or pre-release scenario.
Guardrail: Practice cannot replace the annual live brief, specified Python environment, clean-copy rule, restricted examination files or Surpass upload process.
Memory anchors
Protocol
An agreed set of rules that lets devices format, transmit and interpret data consistently.
Packet switching
Data is split into addressed packets that may take different routes and are reassembled at the destination.
IP and MAC address
An IP address supports routing between networks; a MAC address identifies a network interface locally.
Social engineering
Manipulating people into revealing information or performing an unsafe action.
Encryption
Transforming plaintext into ciphertext so that only someone with the appropriate key can read it.
Defence in depth
Multiple complementary controls reduce reliance on any single safeguard.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which feature makes a school-site network a LAN?
A company links offices in Cardiff and Swansea. Which network type is most likely?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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