Network Security, Encryption & Viruses MCQs with Answers
Solved Network Security, Encryption & Viruses MCQs with answers — DES, AES, WEP, phishing, malware, DoS & hackers. Free quiz + PDF for PPSC, FPSC, NTS, CSS & PMS.
Network Security, Encryption & Viruses — Master Reference for Pakistani Competitive Exams
The chapter Network Security, Encryption & Viruses is a high-frequency Computer Science topic in Pakistan’s PPSC, FPSC, NTS, CSS, PMS, OTS, CTS, BPSC, KPPSC and SPSC One Paper exams. Almost every Junior Clerk, Tehsildar, Sub-Inspector, Computer Operator, Data Entry Operator, Lecturer and BPS-14 to BPS-17 paper carries 3–5 MCQs from this chapter — plus dedicated cyber-security questions for FIA, ASF and IT-cadre tests. This page consolidates solved MCQs with answers covering the three objectives of network security (Identification, Authentication, Access Control), all major encryption standards (DES, AES, WEP), public-key cryptography, digital certificates, and the full taxonomy of cyber threats — virus, worm, trojan horse, spyware, malware, spam, smurfing, DoS attack, e-mail bombing, spear phishing, honey pot. For wider context, see the Wikipedia overview of Network Security and the NIST Cybersecurity Framework — the US standards body whose AES selection underpins modern encryption.
The Six Pillars of Network Security
Analyse → Plan → Design → Implement → Operate → Ongoing Training. Modern network security is a continuous lifecycle, not a one-time project.
Three Objectives of Network Security
| Objective | Description |
|---|---|
| Identification | User-ID — combination of username, student number etc — that says who the user is. |
| Authentication | The process of verifying the identity of a user (passwords, OTPs, biometrics). |
| Access Control | Security features that determine what the authenticated user is allowed to do. |
Encryption — Key Terms
| Term | Definition |
|---|---|
| Encryption | Transforming readable plain text into unreadable cipher text using a key. |
| Decryption | Reverse process — making encrypted text readable again. |
| Cipher | The algorithm used in encryption. |
| Plain Text | The text that gets transformed. |
| Cipher Text | The transformed (encrypted) output. |
| Key | Unique piece of information used to create & reverse the cipher text. |
| Cryptography | Study of creating and using encryption / decryption techniques. |
| Public Key Cryptography | Two keys — public key encrypts, private key decrypts. |
| Digital Certificate | Electronic document that secures internet transactions. |
Encryption Standards
| Standard | Full Name | Details |
|---|---|---|
| DES | Data Encryption Standard | Takes a 64-bit block of data and subjects it to 16 levels of encryption. |
| AES | Advanced Encryption Standard | Selected by the US government to replace DES. |
| WEP | Wired Equivalent Privacy | Wireless encryption standard — broken already in 2001. |
Cyber Threats — Quick Reference
| Threat / Term | Description |
|---|---|
| Virus | Small programme that changes how a computer operates. |
| Worm | Self-replicating; spreads across networks without human help. |
| Trojan Horse | Looks harmless but contains malicious code. |
| Spyware | Secretly monitors user activity. |
| Malware | Any malicious software targeting systems. |
| Spam | Unsolicited bulk email or messages. |
| Smurfing | Network attack exploiting IP broadcast addressing. |
| DoS Attack | Bombards a site with messages to deny service. |
| E-mail Bombing | Excessive unwanted emails sent to a target. |
| Spear Phishing | Targeted scam aimed at a specific individual / org. |
| Honey Pot | Indirect form of network surveillance — a trap for attackers. |
| Hacker | A person who enjoys learning details about computers and how to enhance their capabilities (often used pejoratively for illegal access). |
Other Key Facts to Memorise
- SATAN — Security Analysis Tool for Auditing Networks.
- Functional authorisation — Concerned with individual user rights.
- Auditing — Done to keep an eye on wrongdoings.
- Transposition-based cipher — Order of plain text is NOT preserved.
- Mono alphabetic substitution-based cipher — A character is replaced with some other character (or characters) based on a key.
- WEP — Was broken already in 2001.
Exam tip: Lock six anchors and you cover ~80% of all MCQs from this chapter — 3 objectives (Identification / Authentication / Access Control), DES = 64-bit / 16 rounds, AES replaced DES, Public key encrypts / Private key decrypts, Worm = no human help, and Honey Pot = indirect surveillance.
Frequently Asked Questions
The three objectives of network security are Identification, Authentication and Access Control. User-ID is part of identification, authentication verifies user identity, and access control determines what an authenticated user is allowed to do.
Encryption transforms plain text into unreadable cipher text using a cipher and a key. Decryption is the reverse — making the encrypted text readable again using the correct key.
DES stands for Data Encryption Standard. It takes a 64-bit block of data and subjects it to 16 levels of encryption. DES has since been replaced by AES (Advanced Encryption Standard), which was selected by the US government.
A virus is a small programme that changes the way a computer operates and usually requires user action to spread. A worm copies itself from one system to another over a network without human assistance.
Spear phishing is a targeted email or electronic communications scam aimed at a specific individual, organisation or business — unlike generic phishing which is mass-distributed.
Public key cryptography uses two keys — a public key and a private key. The public key encrypts the message, and the corresponding private key decrypts it.
Yes — essential. Cyber-security & encryption MCQs are tested in every One Paper, NTS NAT, GAT, OTS, CTS, BPSC, KPPSC, SPSC, PPSC, FPSC and FIA / ASF cyber-cadre paper. Expect 3–5 MCQs in any 100-mark paper, more in IT-specific posts.
Yes. Click the Download PDF button to get all Network Security, Encryption & Viruses MCQs with correct answers as a branded QuizWing PDF for offline revision.