Cyber Security
🔒 Log in to trackPreventive measures and security tools
🔒 Log in to track| Measure | What it does |
|---|---|
| Antivirus/anti-malware | Scans, detects, quarantines malware (Windows Defender - built-in; Norton, McAfee, Kaspersky, Quick Heal, Avast) - needs regular virus-definition updates |
| Firewall | Monitors incoming/outgoing traffic against allow/deny rules; hardware or software |
| Updates/patches | Close known vulnerabilities (WannaCry spread through unpatched systems) |
| Strong passwords | Long, mixed-case + digits + symbols, unique per site; avoid names/DOB; passphrase style |
| 2FA/MFA + OTP | A second factor beyond the password |
| Backups | Regular offline/off-site copies defeat ransomware |
| Encryption | Renders stolen data unreadable; HTTPS for web |
| VPN | Encrypted tunnel on public Wi-Fi |
| Digital signature | Verifies sender authenticity + message integrity (issued via Certifying Authorities) |
| Biometrics | Fingerprint/face/iris authentication |
| CAPTCHA | Human-vs-bot test on forms |
| Safe habits | Don't click unknown links/attachments; scan USB drives; avoid pirated software; log out; lock screen (Win+L) |
Antivirus is reactive/detective; a firewall is preventive/gatekeeping - exam options often swap their roles.
Detailed notes
The defence line-up
| Defence | What it does |
|---|---|
| Firewall | a barrier (hardware/software) that monitors and filters traffic between your network and the outside, by rules — allow or block |
| Antivirus | detects and removes malware, mainly by matching virus signatures — so it must be updated regularly |
| Encryption | scrambles data so only the key-holder can read it — plaintext (readable) to ciphertext (scrambled); reading back is decryption |
| Two-factor authentication (2FA) | password plus a second proof — OTP on phone, fingerprint — so a stolen password alone is useless |
| Backup | a safe copy of data kept separately, so ransomware or disk failure cannot erase you |
| Updates/patches | fixes for newly discovered security holes — unpatched systems stay open doors |
Firewall vs antivirus — the roles exams swap
A firewall guards the doorway: it watches network traffic in and out and blocks what breaks the rules — it does not clean infections. Antivirus works inside: it scans files and memory and removes malware that got in — it does not filter network traffic. A machine can have both, and each answers a different exam line: "which filters incoming/outgoing traffic?" = firewall; "which detects and removes viruses?" = antivirus.
Encryption — the one diagram
Plaintext (HELLO) is fed with a key through an encryption algorithm to produce unreadable ciphertext; the receiver applies the key to decrypt. AES (Advanced Encryption Standard) is the widely used modern standard. When you see the padlock and https:// in a browser, the web session is encrypted — the S means Secure. Encryption protects data even if it is stolen in transit; it is why open public Wi-Fi without HTTPS is risky.
Password hygiene and safe habits
- Long passwords mixing letters, digits and symbols; never name, birthdate, or 123456; different password for each important account; changed periodically.
- 2FA everywhere it is offered — the OTP is the second lock.
- Never share OTPs/PINs; banks never ask for them. Do not click links in unknown mails; download software only from official sources; keep the OS and antivirus updated; take backups.
Quick revision
- Firewall filters traffic by rules; antivirus finds and removes malware; they are not the same job.
- Encryption: plaintext + key = ciphertext; decryption reverses it; AES = the standard; https = encrypted web.
- 2FA = password + OTP/biometric — a stolen password alone fails.
- Backups defeat ransomware; updates close known holes.
Types of questions asked
Every way this subtopic shows up in exams — how to recognise it, the formula or logic to use, and a solved example.
Type 1: Firewall purposevery common3 practice Q
'A firewall is used for', 'which device/software filters traffic between networks by rules', hardware-or-software barrier statements.
- Firewall = rule-based barrier between your network and the outside — allows or blocks traffic.
- It filters the doorway; it does not scan or clean infected files.
- Can be hardware, software or both.
Example: The security system that monitors and filters data entering or leaving a network according to rules is a:
Firewall — the doorman of the network.
Type 2: Antivirus vs firewall rolescommon3 practice Q
'Which removes an infection already inside', odd-one-out items where one role is swapped between firewall and antivirus.
- Antivirus scans, detects and removes malware, chiefly by signature matching — so updates are compulsory.
- Firewall filters traffic; antivirus cleans inside — the swap is the classic trap.
- Neither replaces the other; a protected machine keeps both.
Example: Which tool detects and removes a virus that has already entered a computer?
Antivirus — firewall could not have let it in if configured well, but only antivirus cleans inside.
Type 3: Password hygiene and 2FAvery common4 practice Q
'Strong password' pick-the-best-option, 'two-factor authentication means ___', scenarios where a password alone failed.
- Strong = long, mixed (letters+digits+symbols), no name/birthdate/123456, unique per account.
- 2FA = password + a second proof (OTP, fingerprint) — a stolen password alone is not enough.
- Never share OTP/PIN; banks never ask for them — any such message is fraud.
Example: Which of these is the STRONGEST password?
A long mix of letters, digits and symbols unique to that account — not a name, birthdate or 123456.
Type 4: Encryption basics (plaintext, ciphertext, AES, https)common4 practice Q
'Scrambled unreadable data is called ___', 'plaintext to ciphertext', 'the padlock/https means ___', 'AES is a ___'.
- Readable original = plaintext; scrambled form = ciphertext; reversing = decryption, done with the key.
- AES = Advanced Encryption Standard, the widely used modern standard.
- https + padlock = encrypted web session — the S stands for Secure.
Example: Data that has been scrambled so that unauthorised people cannot read it is called:
Ciphertext — the encrypted form; plaintext is the readable original.
Shortcut tricks
⚡ AV detects, FW decides
Antivirus = detective (scans files for malware already arriving); Firewall = gatekeeper (allows/blocks traffic by rules). 'Filters network traffic' -> firewall; 'removes virus from a file' -> antivirus.
Example: Which tool filters network traffic based on defined rules?
Firewall.
⚡ 2FA two doors
Two-factor = knowledge (password) + possession/inherence (OTP, token, fingerprint). One stolen password opens only the first door.
Example: Password + OTP at login is an example of?
Two-factor authentication.
Where students lose marks
Treating antivirus as the network gatekeeper - that is the firewall's role.
Thinking updated antivirus alone guarantees safety - zero-days and phishing bypass it.
Writing passwords on sticky notes or reusing one password everywhere - both kill the 'strong password' measure.
Practice sets — 16 questions
Sets of 10, mixed across the question types above. Each answer comes with a step-by-step explanation.
Topic test · 10 questions
Suggested time 4 min · wrong answers go to your mistake notebook automatically.