Hard Level – GK Questions

LRU cache requires O(1) access and O(1) reorder on access. Hash map provides O(1) key lookup; doubly linked list maintains usage order with O(1) move-to-front. Combined, they achieve O(1) get/put operations. Classic system design question for SSC JE and banking IT exams.

Crystal oscillators use piezoelectric quartz crystals whose resonant frequency depends on physical dimensions (thickness, shape) and crystal cut (AT, BT, SC). Thinner crystals resonate at higher frequencies. Used for precise clock generation in microcontrollers, communication systems, and digital circuits. Temperature-compensated (TCXO) and oven-controlled (OCXO) variants improve stability.

5GC (5G Core) uses service-based architecture (SBA) with cloud-native principles: microservices, containerization, CI/CD. Contrasts with 4G EPC's monolithic design. Benefits: flexibility, scalability, faster feature deployment, and network slicing support. IMS (IP Multimedia Subsystem) handles voice/video services and works with both EPC and 5GC.

Adversarial Debiasing uses adversarial networks to remove correlations between protected attributes (gender, caste) and model predictions while preserving task performance. Other techniques: reweighting samples, bias-aware preprocessing, fairness constraints in loss function. Critical for ethical AI in hiring, lending, and public services where bias can perpetuate inequality.

Network Slicing creates multiple logical networks on shared physical 5G infrastructure, each optimized for specific requirements: ultra-reliable low latency (autonomous vehicles), massive IoT (sensors), enhanced mobile broadband (video). Enables customized QoS, security, and management per slice. Critical for monetizing 5G across industries.

Transparency (Explainable AI/XAI) ensures AI decisions are interpretable by humans, enabling trust, debugging, and regulatory compliance. Techniques: LIME, SHAP, attention visualization. Critical in high-stakes domains: healthcare diagnosis, loan approvals, criminal justice. Balances model complexity with interpretability needs.

RBI Regulatory Sandbox enables fintech startups and banks to test new products/services with real customers under relaxed regulations for limited period/time/scale. Reduces time-to-market, fosters innovation while managing risks. Themes include retail payments, KYC, lending, cybersecurity. Successful pilots may lead to regulatory framework updates.

Model-based imputation (MICE, Bayesian) models relationships between variables to predict missing values, accounting for uncertainty. More robust than simple methods for complex missingness patterns.

Code LLMs enable natural language to code generation, debugging, documentation.

Advanced decoding: beam search explores multiple hypotheses, nucleus sampling truncates low-probability tokens. Balance diversity and coherence.

Spiking neurons fire only when needed; event-driven processing handles only changes. Combined enable orders-of-magnitude better energy efficiency than GPUs for edge AI.

DNA computing leverages biochemical reactions for parallel problem-solving. Research stage with potential for combinatorial optimization, cryptography, archival storage.

Grover's Algorithm searches unsorted database of N items in O(√N) queries vs O(N) classically. Applications: optimization, cryptography, machine learning enhancement.

Differential Privacy adds mathematical noise to model outputs, providing provable privacy guarantees against membership inference and model inversion attacks.

Backdoor attacks inject malicious patterns during training that cause targeted misclassification when trigger present. Critical threat requiring robust training data validation.

Software-Defined Perimeter (SDP) creates identity-based perimeters; micro-segmentation isolates workloads. Both implement Zero Trust by limiting access to authenticated, authorized entities only.

Cellular computing uses biochemical reactions in cells for parallel computation. Early research stage.

Molecular computing uses DNA, proteins, or cellular processes for massive parallelism. Research stage with potential for ultra-low power, complex problem solving.

QEC codes (surface code, Shor code) encode logical qubits across many physical qubits to detect/correct errors. Critical for fault-tolerant quantum computing.

Randomized smoothing provides certified robustness guarantees against adversarial perturbations by averaging predictions over noisy inputs.