D686 Operating Systems for Computer Scientists - Set 4 - Part 1

Correct Answer: Double buffering

Double buffering loads next segment while current plays, switching buffers seamlessly to prevent interruption, ensuring smooth continuous playback without gaps or stuttering occurring.
Option b is incorrect because memory compression reduces space usage but doesn't address the need for continuous data availability during streaming playback requirements fundamentally.
Option c is incorrect because demand paging loads data when accessed causing delays, opposite of the preloading needed for uninterrupted streaming experiences required.
Option d is incorrect because cache eviction removes data to free space, contradicting the goal of maintaining buffered content for smooth playback continuity.

Correct Answer: Global clock

Global clock provides unified time reference enabling precise synchronization of all actuators, preventing collisions and ensuring coordinated movement in complex robotic systems effectively.
Option a is incorrect because polling loops check status repeatedly but don't provide the precise timing synchronization needed for coordinated multi-actuator movements in robotics.
Option c is incorrect because local timers operate independently potentially drifting apart, causing dangerous desynchronization in coordinated robotic movements requiring precision timing critically.
Option d is incorrect because event flags signal occurrences but don't provide the continuous time synchronization required for smooth coordinated actuator control needed.

Correct Answer: Uninterruptible operation

Uninterruptible operation maintains system continuity during power source transitions, preventing any disruption to critical flight control functions during switchover events occurring unexpectedly.
Option a is incorrect because battery backup provides alternate power but doesn't ensure seamless transition without interruption during the switching process itself happening.
Option c is incorrect because power monitoring detects issues but doesn't provide the continuous operation during transitions that critical systems require fundamentally needed.
Option d is incorrect because voltage regulation stabilizes power levels but doesn't address continuity during source switching that flight systems demand for safety.

Correct Answer: Memory integrity checking

Memory integrity checking continuously validates game memory regions detecting unauthorized modifications like wallhacks or aimbots that manipulate game data for cheating advantages unfairly.
Option a is incorrect because file checksums verify game files on disk but don't detect runtime memory modifications that many cheats perform dynamically during gameplay.
Option c is incorrect because network monitoring catches network-based cheats but misses local memory manipulation that doesn't involve network communication at all fundamentally.
Option d is incorrect because process listing shows running programs but doesn't detect subtle memory modifications within legitimate game process space occurring internally.

Correct Answer: Mandatory auditing

Mandatory auditing automatically records all access attempts to patient data, creating compliance-required trails showing user identity, time, and actions for regulatory requirements.
Option a is incorrect because password protection controls access but doesn't create the detailed audit trails required for healthcare compliance and investigation needs specifically.
Option c is incorrect because file encryption protects data confidentiality but doesn't track access patterns needed for compliance audit trail requirements in healthcare.
Option d is incorrect because network isolation prevents external access but doesn't provide the access logging required for regulatory compliance audit trails needed.

Correct Answer: Automatic restart

Automatic restart services detect application failures and restart them without intervention, maintaining display continuity critical for unattended digital signage deployments operating continuously required.
Option a is incorrect because manual restart requires human intervention impossible for unattended digital signage systems deployed in remote or inaccessible locations typically installed.
Option c is incorrect because error messages inform about problems but don't restore operation, leaving displays blank until someone manually intervenes to fix issues.
Option d is incorrect because debug mode helps diagnose problems but doesn't provide the automatic recovery needed for continuous display operation requirements fundamentally necessary.

Correct Answer: Event-driven messaging

Event-driven messaging transmits only when changes occur, conserving battery by avoiding unnecessary communication while ensuring immediate notification of important environmental changes detected effectively.
Option a is incorrect because continuous streaming rapidly drains batteries through constant transmission regardless of whether meaningful changes occur in the environment monitored continuously.
Option c is incorrect because periodic polling wastes energy checking at intervals even when nothing changes, and may miss events between polling cycles occurring.
Option d is incorrect because broadcast updates send to all devices consuming power unnecessarily on receivers that don't need the information being transmitted broadly.

Correct Answer: Store-and-forward operation

Store-and-forward operation queues transactions locally during outages then transmits them when connectivity restores, ensuring business continuity without losing sales or data integrity.
Option a is incorrect because remote processing requires active network connectivity, exactly what's unavailable during outages when offline capability is needed most critically.
Option c is incorrect because cloud backup preserves data but requires connectivity to function, not helping during network outages when local operation is required.
Option d is incorrect because network redundancy provides alternate paths but doesn't enable truly offline operation when all network connectivity is completely unavailable temporarily.

Correct Answer: Edge processing

Edge processing enables onboard decision-making for immediate obstacle avoidance without communication latency, critical for safe autonomous flight in dynamic environments with obstacles present.
Option a is incorrect because remote control introduces communication delays unacceptable for split-second obstacle avoidance decisions required during autonomous drone flight operations critically needed.
Option c is incorrect because cloud computation adds network latency making real-time obstacle response impossible when immediate local decisions are required for safety fundamentally.
Option d is incorrect because batch processing groups operations for efficiency but can't provide the instant response needed for dynamic obstacle avoidance requirements immediately.

Correct Answer: Write-once storage

Write-once storage physically prevents modification after writing, guaranteeing log integrity for audit compliance where tampering could hide fraudulent activities or regulatory violations potentially.
Option a is incorrect because regular backups preserve copies but don't prevent tampering with original logs before backup occurs, compromising audit integrity potentially fundamentally.
Option c is incorrect because encrypted files protect confidentiality but can still be modified or deleted if encryption keys are available to attackers potentially.
Option d is incorrect because hidden directories obscure location but provide no protection against modification by users with sufficient privileges to access them anyway.

Correct Answer: Extended timeouts

Extended timeouts accommodate long satellite propagation delays preventing premature connection termination while maintaining reliability despite seconds of round-trip latency inherent in satellite communications naturally.
Option a is incorrect because standard timeouts assume terrestrial latencies causing connections to fail with satellite delays before legitimate responses can arrive back successfully completing.
Option c is incorrect because protocol switching doesn't solve the fundamental timeout issue; satellite links need TCP's reliability with adjusted timing parameters not different protocols.
Option d is incorrect because dropping connections defeats the purpose; the goal is maintaining connectivity despite delays not terminating due to latency inherently present.

Correct Answer: Fair-share scheduling

Fair-share scheduling divides available power proportionally among vehicles, ensuring equitable charging progress for all users rather than allowing some to monopolize capacity unfairly.
Option a is incorrect because maximum power to each vehicle would exceed station capacity when multiple vehicles connect, requiring intelligent sharing not maximum allocation attempted.
Option c is incorrect because priority charging favors certain users creating unfairness unless emergency vehicles need precedence, not the typical fair allocation scenario described.
Option d is incorrect because random selection could leave some vehicles without power while others charge fully, creating unfair and inefficient power distribution patterns occurring.

Correct Answer: Checksum verification

Checksum verification mathematically validates data integrity by comparing calculated values against stored checksums, detecting any corruption that occurred during backup storage or transmission processes.
Option a is incorrect because file counting only verifies quantity not content integrity; files could be corrupted while count remains correct misleading verification attempts made.
Option c is incorrect because size comparison might detect truncation but misses corruption within files where size remains unchanged despite data errors present internally.
Option d is incorrect because date checking verifies timestamps not data integrity; files could be corrupted while maintaining their original modification dates incorrectly suggesting validity.

Correct Answer: Fail-safe mode

Fail-safe mode automatically transitions systems to safe configurations when detecting anomalies, preventing dangerous conditions even if control systems fail protecting equipment and personnel effectively.
Option a is incorrect because warning alerts notify operators but don't automatically prevent dangerous conditions if humans don't respond quickly enough to prevent accidents potentially.
Option c is incorrect because performance throttling reduces speed but might not eliminate danger; some processes need complete shutdown not just slowing for safety assurance.
Option d is incorrect because activity logging records events for analysis but doesn't actively prevent dangerous conditions from developing during anomaly situations occurring unexpectedly suddenly.

Correct Answer: Real-time patches

Real-time patches modify kernel scheduling and preemption behavior, providing deterministic low-latency response essential for professional audio processing without dropouts or delays occurring during production.
Option a is incorrect because generic drivers provide compatibility but lack optimizations for low-latency audio processing that professional music production requires for quality results achievable.
Option c is incorrect because standard scheduling prioritizes fairness over latency, causing audio dropouts when other processes interfere with time-critical audio processing needs occurring.
Option d is incorrect because default buffers are sized for general use causing latency; professional audio needs minimal buffers for real-time responsiveness during processing.

Correct Answer: Inverted indexes

Inverted indexes map terms to document locations enabling fast lookups without scanning entire dataset, essential for search engine performance with billions of documents indexed comprehensively.
Option a is incorrect because linear lists require sequential scanning taking too long for billions of documents; search engines need faster access methods than linear searching.
Option c is incorrect because hash tables provide fast single-key lookup but don't efficiently support complex queries with multiple terms that search engines handle regularly.
Option d is incorrect because binary trees improve search but still require traversal; inverted indexes provide direct term-to-document mapping for instant access needed essentially.

Correct Answer: Tiered storage

Tiered storage automatically migrates aging footage from fast expensive storage to slower cheaper media, optimizing costs while maintaining accessibility based on data age appropriately.
Option a is incorrect because random storage doesn't consider access patterns or age, missing optimization opportunities for cost-effective surveillance footage storage management over time generally.
Option c is incorrect because temporary storage implies deletion not migration; surveillance systems need long-term retention with cost-optimized storage not deletion after time passes.
Option d is incorrect because compressed storage reduces size but doesn't address the speed versus cost tradeoff that tiered storage manages for different footage ages.

Correct Answer: Hardware acceleration

Hardware acceleration uses low-power chips for wake word detection, keeping main processors sleeping until triggered, dramatically reducing power consumption during continuous listening periods effectively implemented.
Option a is incorrect because full processing keeps main CPU active continuously monitoring audio, rapidly draining batteries in mobile devices during always-on listening states unnecessarily.
Option c is incorrect because software loops require CPU activity consuming significant power compared to dedicated low-power hardware designed for pattern matching specifically optimized efficiently.
Option d is incorrect because cloud detection requires network transmission and remote processing, consuming more power than local hardware acceleration for wake word detection inherently.

Correct Answer: Redundant sensing

Redundant sensing correlates data from cameras, magnetic loops, and ultrasonic sensors, maintaining accuracy when individual sensors fail through cross-validation and voting mechanisms implemented effectively.
Option a is incorrect because single sensors create single points of failure; one malfunction causes incorrect occupancy reporting affecting entire parking management system reliability fundamentally.
Option c is incorrect because manual counting requires human labor and can't provide real-time updates that automated parking systems need for driver guidance continuously.
Option d is incorrect because random sampling misses vehicles and provides incomplete coverage; parking systems need comprehensive monitoring not statistical estimates for accuracy required.

Correct Answer: Dynamic rerouting

Dynamic rerouting continuously recalculates optimal paths incorporating new orders and traffic conditions, maximizing delivery efficiency compared to static pre-planned routes saving time significantly achieved.
Option a is incorrect because fixed routes can't adapt to new orders or changing conditions, missing optimization opportunities that dynamic adjustment provides for efficiency gains possible.
Option c is incorrect because random assignment ignores geography and timing, creating inefficient routes that waste time and fuel compared to optimized routing algorithms available.
Option d is incorrect because sequential delivery by order time ignores geographic clustering, causing unnecessary travel between distant locations reducing delivery efficiency significantly observed practically.