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50 highly-asked Microservices interview questions

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Basics & Definition

  1. What is microservices architecture?
  2. How does microservices differ from monolithic architecture?
  3. What are the advantages of microservices?
  4. What are the drawbacks or challenges of microservices?
  5. What are the key characteristics of a microservices design?
  6. Describe domain-driven design (DDD) in microservices.
  7. What is the Single Responsibility Principle and how it applies to microservices?
  8. Explain loose coupling and high cohesion in microservices.

Communication & Interaction

  1. How do microservices communicate? (REST, gRPC, messaging)
  2. What is synchronous vs asynchronous communication?
  3. What are event-driven microservices?
  4. How would you handle retries and fallbacks?
  5. What is idempotence and why does it matter?
  6. Explain eventual consistency.
  7. What is a consumer-driven contract (CDC)?

Service Discovery & API Routing

  1. What is service discovery and why is it needed?
  2. Compare client-side vs server-side discovery.
  3. What is an API Gateway and its responsibilities?
  4. Explain service registry (Eureka, Consul, etc.).
  5. When would you use load balancers?

Security

  1. How would you secure microservices? (OAuth2 / JWT)
  2. What are the limitations of Basic Auth in microservices?
  3. Explain mutual TLS and when it’s useful.
  4. How do API Gateways help with security?
  5. What is zero-trust security & why is it important?

Data Management

  1. Should every microservice have its own database? Why?
  2. What is the database-per-service pattern?
  3. How do you handle distributed transactions? (SAGA, 2PC)
  4. What is change data capture (CDC)?
  5. What is event sourcing and CQRS in microservices?

Testing

  1. How do you test microservices? Unit, integration, e2e tests.
  2. What are contract tests?
  3. What challenges exist for microservices testing?
  4. Describe end-to-end testing strategy in distributed systems.

DevOps, CI/CD & Deployment

  1. How do you deploy microservices independently? (CI/CD pipelines)
  2. What is blue-green deployment?
  3. What is canary deployment?
  4. How do you handle configuration management? (Config Server etc.)
  5. How does containerization help microservices? (Docker)
  6. What is the role of Kubernetes in microservices?

Observability (Logging, Monitoring, Tracing)

  1. What is centralized logging?
  2. How do you implement distributed tracing? (Jaeger / Zipkin)
  3. What is a correlation ID?
  4. How do you monitor microservices performance? (Prometheus/Grafana)

Resilience & Fault Tolerance

  1. What is a circuit breaker?
  2. What are bulkheads & rate limiting?
  3. How do you handle fallback strategies?
  4. How do you design for failures?

Advanced Design / Scenario Questions

  1. How would you design a microservices system for a large e-commerce platform?
  2. Explain trade-offs between microservices and monolithic architecture (performance, scaling, cost).