Java

1. How does ConcurrentHashMap achieve thread safety?
2. Virtual Threads vs Platform Threads?
3. How do you diagnose high CPU usage in a Java application?
4. How do you identify and fix memory leaks?
5. Explain G1 GC, ZGC, and Shenandoah. When would you choose each?
6. What happens internally when a Full GC occurs?
7. How do you optimize a high-throughput Java application?
8. Explain Java Memory Model (JMM).
9. What causes thread starvation and deadlocks?
10. How does the ForkJoinPool work?
11. What is False Sharing and how can it impact performance?
12. How would you profile a production JVM?
13. What are the limitations of Virtual Threads?
14. How does CompletableFuture work internally?
15. How would you design a thread-safe cache?

Microservices

16. How would you design a fault-tolerant microservice architecture?
17. How do you prevent cascading failures?
18. Circuit Breaker vs Retry Pattern?
19. How would you implement distributed transactions?
20. Saga Choreography vs Saga Orchestration?
21. What are the drawbacks of microservices?
22. How do you handle service-to-service communication?
23. REST vs gRPC in microservices?
24. How do you implement idempotency?
25. How do you handle API versioning?
26. How would you design a notification system?
27. How would you secure internal microservice communication?
28. What happens when one microservice is unavailable?
29. How do you handle eventual consistency?
30. How would you debug a slow microservice?

Kafka

31. How does Kafka achieve high throughput?
32. What causes consumer lag?
33. How do you handle duplicate messages?
34. Explain Kafka partitioning strategy.
35. How do you guarantee message ordering?
36. What is exactly-once processing?
37. What happens when a Kafka broker fails?
38. How would you design a Dead Letter Queue strategy?
39. Kafka vs RabbitMQ?
40. How do you replay historical events safely?

Kubernetes

41. What happens when a Pod crashes?
42. Difference between Deployment, StatefulSet, and DaemonSet?
43. How does Kubernetes Service Discovery work?
44. What are Readiness and Liveness probes?
45. How do you troubleshoot a CrashLoopBackOff?
46. What causes pod eviction?
47. HPA vs VPA?
48. How would you scale a Java application in Kubernetes?
49. How do you manage secrets securely?
50. What happens during a rolling deployment?

AWS

51. EC2 vs ECS vs EKS?
52. When would you choose Lambda over ECS?
53. SQS vs SNS?
54. How does S3 achieve durability?
55. How do you secure applications in AWS?
56. RDS vs DynamoDB?
57. What is AWS Auto Scaling?
58. How would you design a highly available application in AWS?
59. What is the difference between ALB and NLB?
60. How do you troubleshoot high latency in AWS?