4.2 Network issues and communication
Cambridge IGCSE ICT 0417 · Topic 4: Networks and the effects of using them · Paper 1
5.2 Potential health problems
Cambridge IGCSE ICT 0417 · Topic 5: The effects of using IT · Paper 1
6.8 Expert systems
Cambridge IGCSE ICT 0417 · Topic 6: ICT applications · Paper 1
Say each word, then read what it means. Every one is in the glossary too.
Read it here, or open the study page below to go one step at a time with things to try.
Data on a network can be intercepted, changed or stolen. Networks also spread malware quickly.
Authentication means proving that a user is who they say they are, before they get access.
Common protections: user IDs and passwords, firewalls, encryption of data being sent, and anti-malware software.
A weak password is short or easy to guess: a name, a birthday, a word from the dictionary, `123456` or `password`.
A strong password is long and mixes upper-case letters, lower-case letters, numbers and symbols. It is not a real word and is not linked to the user.
Each extra character multiplies the number of possible passwords. So length matters most. Type passwords into the checker and watch the time to crack change.
A strong password is still unsafe if it is reused on many sites, written on a sticky note, or never changed after a data breach.
There is something to try for this step in the IGCSE library.
Passwords are the most common method. They are cheap and easy, but can be guessed, forgotten, seen by shoulder surfing or stolen by spyware.
Biometrics use a unique part of a person's body or behaviour: fingerprint, face, iris or retina, voice or handwriting.
| Biometric | Advantage | Disadvantage |
|---|---|---|
| Fingerprint | Quick and cheap; unique to each person | Dirty or cut fingers may not be recognised |
| Face recognition | No contact needed | Lighting, glasses, beards or ageing can cause errors |
| Iris / retina scan | Very accurate and very hard to fake | Expensive; retina scanning is intrusive |
| Voice recognition | Works over the phone; no extra hardware on a phone | Colds and background noise cause errors; can be recorded and replayed |
Biometrics are more secure than passwords because a body feature cannot be forgotten, shared or easily guessed.
A magnetic stripe card holds data such as a staff ID on its stripe. It is swiped to open doors. Cheap, but easy to copy and damaged by magnets.
A smart card has a chip that stores and processes data, often with an RFID antenna. It is harder to copy and can hold more data. Often used with a PIN.
A physical token is a small device that shows a one-time password (OTP). Some need the user's PIN first. Banks use them for online banking.
An electronic token is software, usually an app on a phone, that creates a one-time code or approves a log-in. Codes change every 30 to 60 seconds, so a stolen code is soon useless.
A token's code is a one-time password. Say why it helps: even if it is intercepted, it cannot be used again.
Zero login is a way of authenticating without typing anything. The system recognises the user from biometrics and behaviour, such as how they hold the phone, how they type and where they usually are.
Advantage: very convenient, and nothing to forget.
Disadvantage: the system collects lots of personal data, users may not know they are being tracked, and it is harder to tell how secure it is.
Malware is software designed to harm a computer or steal data, such as viruses, spyware and ransomware.
Anti-malware software (including anti-virus) scans files and emails, compares them with a database of known malware signatures, and watches for suspicious behaviour.
Infected files are quarantined (isolated so they cannot run) or deleted. The software must be updated regularly so it knows about new malware.
On a network, one infected computer can infect all the others, so every device needs up-to-date anti-malware.
Video conferencing uses webcams, microphones, speakers and screens so people in different places can see and hear each other live.
Audio conferencing uses only sound: a phone call with three or more people, or an internet call with no video. Participants often dial a number and type a PIN.
Web conferencing (webinars) runs in a browser or app. As well as video and audio, users can share screens, chat by text, use a whiteboard and vote.
| Advantages (all types) | Disadvantages (all types) |
|---|---|
| No travel, so saves time, money and fuel | Needs a reliable, fast internet connection; lag and dropped calls |
| Meetings can be set up at short notice | Time zones make scheduling hard for international meetings |
| People can join from anywhere, including when ill or abroad | Less personal: body language is harder to read |
| Safer: no travel risks | Equipment costs (webcams, headsets, software licences); security risk if calls are hacked |
The problems come from how we use computers: long periods, bad posture, repeated movements and screens.
In the exam, match each problem to its cause, then give a prevention that removes that cause.
RSI is pain, swelling and stiffness in the fingers, wrists or arms. It is caused by repeating the same small movements for a long time, such as typing, clicking a mouse or texting.
Prevention: take regular breaks, use an ergonomic keyboard and mouse, use a wrist rest, keep wrists straight, and do finger and hand exercises.
An ergonomic device is shaped to fit the body naturally, so muscles and joints are under less strain.
Back and neck pain is caused by sitting in a poor position for a long time, slouching, or a screen that is too high, too low or to one side. Using a laptop on your knees or a phone looking down makes it worse.
Prevention: use an adjustable chair with back support. Put the top of the screen at eye level.
Use a footrest if your feet do not reach the floor. Sit up straight and take breaks to walk around.
Eye strain (tired, sore, dry eyes and blurred vision) is caused by staring at a screen for a long time, glare, flickering screens and poor lighting.
Headaches have similar causes: glare, screen flicker, poor lighting, bad posture and long periods without a break.
Prevention: take regular breaks and look into the distance. A common rule is 20-20-20: every 20 minutes, look 20 feet (6 m) away for 20 seconds.
Also use an anti-glare screen or filter, adjust the brightness, use good lighting with blinds, and have regular eye tests.
| Health problem | Cause | Prevention |
|---|---|---|
| RSI | Repeated typing, clicking, texting for long periods | Regular breaks; ergonomic keyboard and mouse; wrist rest; hand exercises |
| Back and neck problems | Poor posture; badly placed screen; unsuitable chair | Adjustable chair with back support; screen at eye level; footrest; breaks to move |
| Eye strain | Staring at screens; glare; flicker; poor lighting | Regular breaks; anti-glare filter; adjust brightness; blinds; eye tests |
| Headaches | Glare; flicker; poor lighting; long periods at screen | Anti-glare screen; good lighting; regular breaks; eye tests |
Match the prevention to the cause. "Take breaks" fits everything, so examiners often reward it only once. Give a specific second method, like an anti-glare filter for eye strain.
An expert system is software that copies the knowledge and decisions of a human expert in one area.
Uses: medical diagnosis, mineral prospecting (where to dig for oil or metals), car engine fault diagnosis, playing chess, tax advice, and strategy games.
It asks the user questions, applies rules to the answers, and gives a conclusion with a probability, plus an explanation.
Try the expert system below. It finds out why a laptop will not start. Answer its questions and watch the inference engine apply rules from the rules base (the toy calls it the rule base) to the knowledge base. Then read How I decided: that is the explanation.
| Component | What it does |
|---|---|
| User interface | Asks the user questions on screen, usually yes/no or multiple choice, and shows the results. |
| Explanation system | Explains how the system reached its conclusion, and its probability or confidence. |
| Inference engine | The "thinking" part. Applies the rules to the facts and the user's answers to reach conclusions. Decides which question to ask next. |
| Knowledge base | Stores the facts about the subject, collected from human experts. |
| Rules base | Stores the IF … THEN rules that link facts to conclusions. |
Learn the five names exactly. "Database" is not the same as "knowledge base", and "processor" is not "inference engine".
There is something to try for this step in the IGCSE library.
To build one: interview experts to collect knowledge; build the knowledge base and rules base; build the inference engine; design the user interface and explanation system; test it against known cases.
| Advantages | Disadvantages |
|---|---|
| Gives consistent answers; does not get tired or emotional | Only as good as the rules entered; errors give wrong advice |
| Knowledge of many experts in one system | Has no common sense; cannot handle situations outside its rules |
| Available 24/7 and in many places at once, even where there is no expert | Expensive to set up and keep up to date |
| Fast; gives probabilities and explains its reasoning | Users may trust it too much; lacks a human expert's empathy |
Open the study page and go one step at a time.
Step by step, with exam questions and a quiz.
ICT topic 2Step by step, with exam questions and a quiz.
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Topic 15 · Year 7A network is computers connected to share data. The internet is a network of networks. Data travels in small packets, following rules called protocols.
Topic 19 · Year 7Using technology well means staying safe, knowing the laws about computers and data, and asking who technology helps and who it harms.
Topic 18 · Year 7Data is raw facts. Information is data with meaning. Spreadsheets calculate, databases store and search, AI learns patterns from examples.
One question at a time. The reason shows after each answer.