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System Design Objective Questions and Answers - Set 2
This Java System Design quiz contains carefully curated objective questions with correct answers and clear explanations. It is designed for backend engineers, platform engineers, and architects to test your skills across scalable Java architectures, distributed systems, concurrency models, resiliency patterns, cloud-native deployments, and modern performance trade-offs. This is part 2 of the series.
Practice System Design MCQs with Detailed Explanations
Answer at least 12 questions to submit and verify answers.
16 Which deployment strategy minimizes downtime during Java service upgrades? Medium
Correct answer:
Blue-green or canary deployments
Blue-green and canary strategies allow gradual traffic shifting and fast rollback.
17 Which approach best limits blast radius when a Java microservice fails? High
Correct answer:
Service isolation with separate data stores
Isolating services and their data stores reduces the impact of failures across the system.
18 Which pattern improves throughput for batch writes in Java services interacting with databases? Medium
Correct answer:
Batching with prepared statements
Batching reduces round trips and improves throughput for write-heavy workloads.
19 Which approach best handles bursty traffic in a Java API layer? High
Correct answer:
Rate limiting with queues and autoscaling
Rate limiting with queues and autoscaling absorbs bursts while protecting downstream services.
20 Which observability signal is most useful to debug tail-latency issues in Java microservices? Medium
Correct answer:
Distributed tracing with percentiles
Distributed tracing with percentile metrics reveals slow paths causing tail latency.
21 Which design improves scalability of real-time notifications in Java systems? High
Correct answer:
Server push with pub-sub fanout
Pub-sub fanout with server push scales better than polling for real-time updates.
22 Which data model best suits append-only event logs in Java-based platforms? Medium
Correct answer:
Append-only log with immutable events
Append-only immutable event logs improve auditability, scalability, and replayability.
23 Which strategy reduces cold start impact for Java services in containerized environments? High
Correct answer:
Class data sharing and warmup
Class data sharing and warmup reduce startup and warmup latency for JVM-based services.
24 Which API design choice improves backward compatibility in Java microservices? Medium
Correct answer:
Versioned APIs with additive changes
Versioned APIs with additive changes preserve backward compatibility while enabling evolution.
25 Which pattern best prevents duplicate processing in distributed Java schedulers? High
Correct answer:
Leader election with idempotent tasks
Leader election combined with idempotent task execution prevents duplicates under failures.
26 Which approach reduces memory pressure under high object churn in Java services? High
Correct answer:
Reducing allocations and using efficient data structures
Reducing allocations and choosing efficient data structures lowers GC pressure and improves throughput.
27 Which pattern ensures reliable delivery of side effects when a Java service writes to DB and emits events? High
Correct answer:
Transactional outbox pattern
Transactional outbox ensures DB changes and event emission are coordinated reliably.
28 Which approach improves multi-region read performance for Java APIs? High
Correct answer:
Geo-distributed read replicas with caching
Geo-distributed read replicas with caching reduce latency for global users.
29 Which design choice best supports schema evolution in Java event-driven systems? High
Correct answer:
Backward/forward-compatible schemas
Backward and forward compatibility enables safe evolution of event schemas.
30 Which concurrency model reduces contention in high-write Java counters? Medium
Correct answer:
Striped counters or LongAdder
Striped counters reduce contention under high concurrency compared to a single atomic variable.