Medium Level – GK Questions

Proxy servers act as intermediaries between client and internet, masking the user's real IP address. By connecting through a proxy in another country, users can access geo-restricted content. However, many services now detect and block proxy/VPN traffic. Legal and policy considerations apply.

Computer Worm is standalone malware that self-replicates to spread across networks, exploiting vulnerabilities without requiring user action (unlike viruses that need host files). Worms can consume bandwidth, install backdoors, or deliver payloads. Prevention: network segmentation, patching, firewall rules.

COMMIT permanently saves all changes made during a transaction to the database. ROLLBACK undoes uncommitted changes. Transactions follow ACID properties (Atomicity, Consistency, Isolation, Durability). Proper use of COMMIT/ROLLBACK ensures data integrity in multi-user database environments.

Machine Learning enables systems to learn patterns from data and improve performance on tasks without explicit programming. Types: Supervised (labeled data), Unsupervised (pattern discovery), Reinforcement (reward-based learning). Applications: recommendation engines, fraud detection, predictive maintenance.

Virtual memory is a memory management technique where the OS uses a portion of hard disk (page file/swap space) as an extension of physical RAM. Allows running programs larger than available RAM by swapping inactive pages to disk. Slower than physical RAM but enables multitasking and larger address spaces.

Phishing is a social engineering attack where attackers impersonate legitimate entities via email/SMS to trick victims into revealing credentials or installing malware. Unlike technical exploits (buffer overflow, SQL injection), social engineering manipulates human psychology. Training and awareness are key defenses.

AePS (Aadhaar Enabled Payment System) allows bank customers to use Aadhaar number and fingerprint/iris for basic banking transactions at Micro-ATMs through Business Correspondents. Operated by NPCI, it promotes financial inclusion in rural areas without need for cards, phones, or internet.

SSH (Secure Shell) provides encrypted remote login and command execution over insecure networks. Replaces insecure Telnet which transmits data in plaintext. SSH uses public-key cryptography for authentication and supports port forwarding, file transfer (SFTP), and tunneling. Default port: 22.

NavIC (Navigation with Indian Constellation) is India's independent regional satellite navigation system with 7 satellites. Provides positioning accuracy better than 20m over India and 1500 km surrounding area. Used in transportation, disaster management, and mobile devices. GLONASS (Russia), Galileo (EU), BeiDou (China) are other global systems.

PMGDISHA (Pradhan Mantri Gramin Digital Saksharta Abhiyan) aims to make 6 crore rural adults digitally literate by training them to operate computers, access internet, use digital payments, and avail e-governance services. Implemented through Common Service Centres (CSCs) across villages.

2FA significantly reduces risk but doesn't eliminate it. Attackers can bypass 2FA via SIM swapping, phishing for OTPs, malware capturing tokens, or social engineering. Best practice: use authenticator apps or hardware tokens instead of SMS, monitor account activity, and use unique passwords.

DeFi protocols use smart contracts to automate financial services: lending (Aave), trading (Uniswap), derivatives, and yield farming. Operate on public blockchains (Ethereum, Solana) with transparent, permissionless access. Risks include smart contract bugs, volatility, and regulatory uncertainty. Critical for fintech innovation questions.

4D printing uses smart materials (shape-memory polymers, hydrogels) that transform when exposed to heat, moisture, light, or magnetic fields. Applications: self-assembling structures, adaptive medical devices, and responsive textiles. Emerging research area with potential in aerospace, healthcare, and soft robotics.

LIDAR (Light Detection and Ranging) uses laser pulses to create high-resolution 3D maps of surroundings, enabling object detection, classification, and distance measurement. Combined with cameras, radar, and GPS for robust perception. Critical for self-driving cars, drones, and mobile robots. Important for autonomous systems questions.

Coherence time (T1 for energy relaxation, T2 for phase decoherence) determines how many quantum operations can be performed before errors dominate. Longer coherence enables more complex algorithms. Improved via better materials, shielding, and error correction. Critical metric for comparing quantum hardware platforms.

NFT smart contracts can embed royalty clauses (e.g., 5-10%) that automatically pay creators on each resale in secondary markets. Enables sustainable creator economies in metaverse platforms. Implemented on Ethereum, Polygon, and other chains. Critical for digital ownership and creator monetization questions.

ZK-proofs enable one party to prove knowledge of a secret (e.g., valid transaction) without revealing the secret itself. Applications: privacy-preserving cryptocurrencies (Zcash), identity verification, and confidential smart contracts. Computationally intensive but advancing with zk-SNARKs/zk-STARKs. Critical for privacy and scalability questions.

Heat treatment (annealing, stress relieving) reduces residual stresses from rapid melting/solidification in metal AM, improving dimensional stability and mechanical properties. Other post-processing: support removal, machining, surface finishing. Critical for qualifying AM parts for aerospace/medical applications. Important for manufacturing process questions.

Closed-loop control continuously compares desired vs actual state (via sensors) and adjusts actuators to minimize error. Contrasts with open-loop (no feedback). Essential for precision tasks: assembly, welding, autonomous navigation. PID controllers are common implementation. Critical for robotics control theory questions.

Persistence is a defining feature of metaverse: virtual environments, economies, and social interactions continue evolving independently of individual user presence. Enabled by cloud infrastructure, blockchain state, and server-side simulation. Critical for distinguishing metaverse from ephemeral VR experiences or video games.