Cyber Security
🔒 Log in to trackPreventive measures and security tools
🔒 Log in to trackDefences protect a system before, during and after an attack. A firewall filters network traffic. Antivirus finds and removes malware. Encryption scrambles data, 2FA adds a second proof, and backups save you when data is lost.
The defence line-up
| Defence | What it does |
|---|---|
| Firewall | A barrier in hardware or software. It filters traffic between your network and the outside by rules |
| Antivirus | Finds and removes malware, mostly by matching known virus signatures. It must be updated |
| Encryption | Scrambles data so only the key holder can read it |
| Two-factor authentication (2FA) | A password plus a second proof, such as an OTP or fingerprint |
| Backup | A separate safe copy of data |
| Updates and patches | Fixes for security holes that were found |
| VPN | An encrypted tunnel over the internet |
Firewall vs antivirus
The two are often swapped.
- A firewall guards the doorway. It watches traffic in and out and blocks anything that 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.
Rule: Filters incoming and outgoing traffic means firewall. Detects and removes viruses means antivirus.
Encryption in one picture
Plaintext is readable data, such as HELLO. An encryption method and a key turn it into ciphertext, which is unreadable. The receiver uses a key to decrypt it back.
- AES (Advanced Encryption Standard) is a widely used modern method.
- A padlock and HTTPS in the browser mean the session is encrypted. The S stands for Secure.
- Encryption protects data even if someone steals it on the way.
Watch: Public Wi-Fi without HTTPS is risky, because others may read your traffic.
Digital signature
A digital signature proves who sent a document and that nobody changed it. The sender signs with a private key. Anyone can check it with the public key.
Password hygiene
- Use long passwords that mix letters, digits and symbols.
- Never use your name, birth date or 123456.
- Use a different password for each important account.
- Turn on 2FA wherever it is offered.
- Never share an OTP or PIN. Banks never ask for them.
Safe habits
- Do not click links in unknown mail.
- Download software only from official sources.
- Keep the operating system and antivirus updated.
- Take regular backups.
Tip: Backups beat ransomware. If your files are locked, you restore the copy.
Question types you will see
Each type: how to recognise it, the method step by step, and one question to try.
Firewall purpose
The question asks what filters network traffic.
Spot the words filter, monitor or traffic.
Match them to a barrier with rules.
Name it a firewall.
A firewall is the gatekeeper between networks.
Which security tool monitors and filters incoming and outgoing network traffic?
Show solutionHide solution
It works at the network door.
It uses allow or block rules.
Firewall
Antivirus vs firewall roles
Two tools are offered, and one job is described.
Detect and remove malware means antivirus.
Filter traffic means firewall.
Remember antivirus needs regular updates.
The two tools do different jobs on different layers.
Which tool detects and removes viruses from a computer?
Show solutionHide solution
It cleans infections.
That is the antivirus.
Antivirus
Password hygiene and 2FA
The question asks for a strong password rule or the meaning of 2FA.
A strong password is long and mixed.
Never use a name or 123456.
2FA adds a second proof.
A second proof makes a stolen password useless alone.
Login with a password followed by an OTP on the phone is called:
Show solutionHide solution
The password is one factor.
The OTP is a second factor.
Two-factor authentication
Encryption basics
The question mentions plaintext, ciphertext, AES or https.
Plaintext is readable.
Ciphertext is scrambled.
AES is a modern method.
https means encrypted web.
Encryption protects the data itself, not only the path.
Data in unreadable, scrambled form after encryption is called:
Show solutionHide solution
Readable data is plaintext.
The scrambled form is the opposite.
Ciphertext
Backup and updates
The question asks how to recover from ransomware or fix a security hole.
Backups restore lost or locked data.
Updates and patches close known holes.
Both should be regular.
Prevention and recovery both matter.
The best protection against losing files to ransomware is:
Show solutionHide solution
Locked files can be replaced.
A separate copy makes that possible.
Regular backups
Shortcuts that save time
A firewall guards the door, so it watches traffic. Antivirus cleans the room, so it removes malware inside.
2FA needs something you know, such as a password, plus something you have or are, such as an OTP or fingerprint.
A bank sends an OTP after you enter your password. Which security idea is this?
Show solutionHide solution
The password is the first factor.
The OTP is a second proof.
Two-factor authentication
Mistakes to avoid
Where most students lose marks on this subtopic.
Saying antivirus filters network traffic.
A firewall filters traffic. Antivirus removes malware.
Saying a firewall removes viruses.
A firewall blocks traffic by rules. It does not clean infections.
Using the same simple password for every account.
Use a long, different password for each important account.
Thinking ciphertext is readable data.
Plaintext is readable. Ciphertext is the scrambled form.
Ignoring updates because the antivirus is installed.
Antivirus must be updated to know new threats.
Quick revision
Read this the night before the exam.
Firewall filters traffic by rules. Antivirus detects and removes malware.
Encryption turns plaintext into ciphertext with a key. Decryption reverses it. AES is the modern standard.
https and the padlock mean the web session is encrypted.
2FA is a password plus a second proof such as an OTP or fingerprint.
Backups defeat ransomware. Updates close known holes.
A digital signature is signed with the private key and checked with the public key.
Practice: 16 questions
Sets of 10, mixed across the question types above. Every answer has a step-by-step explanation.
Topic test · 10 questions
Suggested time 4 min · wrong answers go to your mistake notebook automatically.