Table of Contents
- Core Microservices Concepts
- Service Communication & APIs
- Scalability & Resilience Patterns
- Data Management in Microservices
- Cloud & AWS Microservices
- Observability (Logging, Monitoring, Tracing)
- Security in Microservices
- CI/CD & DevOps for Microservices
- System Design & Real-World Scenarios
- Tricky & Advanced Questions
- Conclusion
Core Microservices Concepts
- What are microservices and how do they differ from monolithic architecture?
- What are the advantages and disadvantages of microservices?
- Explain the evolution from SOA (Service-Oriented Architecture) to microservices.
- What is bounded context in microservices (Domain-Driven Design)?
- What is loose coupling and high cohesion in microservices?
- How do you decide service boundaries in microservices?
- What is the role of API Gateway in microservices?
- Difference between microservices and serverless architecture.
- How do you ensure fault isolation in microservices?
- What are the common challenges in microservices adoption?
- Explain synchronous vs asynchronous communication in microservices.
- What is the role of orchestration vs choreography in microservices?
- How do you handle versioning of microservices?
- Difference between vertical and horizontal scaling in microservices.
- What is the role of containers (Docker) in microservices?
- Explain the concept of service mesh (e.g., Istio, Linkerd).
- What are common anti-patterns in microservices?
- Explain circuit breaker pattern in microservices.
- How do you handle cross-cutting concerns in microservices?
- Difference between orchestration (Kubernetes) and choreography (event-driven microservices).
Service Communication & APIs
- Difference between REST, gRPC, and GraphQL in microservices communication.
- How do you secure communication between services?
- What are synchronous vs asynchronous communication trade-offs?
- Explain idempotency in API design.
- How do you handle backward compatibility in APIs?
- What is API Gateway throttling and rate limiting?
- Explain service discovery in microservices.
- How do you handle distributed transactions in microservices?
- Difference between client-side discovery and server-side discovery.
- Explain the role of load balancers in microservices.
- What is eventual consistency and why is it important?
- How do you handle API versioning strategies?
- Difference between synchronous API calls and message-driven communication.
- Explain saga pattern in microservices transactions.
- What is compensating transaction in microservices?
- How do you handle retries and backoff in communication failures?
- What are dead-letter queues and their purpose?
- Explain request-response vs publish-subscribe messaging.
- How do you achieve service-to-service authentication?
- What is the role of service registry (Eureka, Consul, Zookeeper)?
Scalability & Resilience Patterns
- Explain the circuit breaker pattern with an example.
- What is bulkhead pattern in microservices?
- How do you implement retry and exponential backoff?
- Explain rate limiting strategies.
- What is the fallback mechanism in microservices?
- How do you design microservices for high availability?
- Difference between active-active and active-passive deployments.
- Explain distributed caching in microservices.
- What is CAP theorem and its relevance in microservices?
- How do you ensure scalability of stateful services?
- What is service throttling and when is it needed?
- Explain chaos engineering in microservices resilience testing.
- How do you prevent cascading failures in microservices?
- What is auto-scaling and how does it work in Kubernetes?
- Explain load shedding in microservices.
- How do you design microservices for disaster recovery?
- What is the role of circuit breakers in Hystrix/Resilience4j?
- Explain leader election in distributed systems.
- How do you handle hotspots in distributed services?
- What are distributed locks and when do you use them?
Data Management in Microservices
- What is database per service pattern?
- How do you handle distributed transactions without 2PC?
- Explain event sourcing in microservices.
- Difference between CQRS and traditional CRUD approach.
- How do you achieve data consistency across services?
- What is the outbox pattern?
- How do you handle schema evolution in microservices?
- Difference between polyglot persistence and single DB approach.
- What are the challenges of sharing a database between microservices?
- Explain eventual consistency with an example.
- What is database sharding and its role in microservices?
- How do you implement distributed caching?
- What is read/write splitting in microservices?
- How do you design a reporting service in microservices?
- Explain saga orchestration for data consistency.
- What is dual-write problem and how to avoid it?
- Difference between synchronous replication and asynchronous replication.
- How do you handle GDPR compliance in microservices data storage?
- What is multi-tenancy in microservices databases?
- How do you monitor data integrity across services?
Cloud & AWS Microservices
- What AWS services are commonly used for microservices architecture?
- Explain AWS ECS vs EKS for running microservices.
- How does AWS Lambda fit into microservices?
- What is the role of API Gateway in AWS?
- How do you design event-driven microservices with AWS SQS and SNS?
- Explain AWS DynamoDB vs RDS in microservices use cases.
- What is AWS Step Functions and its role in orchestration?
- How do you handle service discovery in AWS?
- What is AWS App Mesh?
- How do you monitor microservices in AWS (CloudWatch, X-Ray)?
- Explain difference between ECS Fargate and EC2 launch types.
- What is AWS Elastic Beanstalk and how does it compare with ECS/EKS?
- How do you secure secrets in AWS microservices (Secrets Manager, Parameter Store)?
- Explain CI/CD with AWS CodePipeline and CodeBuild for microservices.
- What is AWS EventBridge and its role in microservices?
- How do you implement blue-green deployment in AWS?
- Explain canary deployments in AWS using CodeDeploy.
- What is VPC and how does networking work in AWS microservices?
- How do you handle inter-region communication in AWS microservices?
- What are AWS well-architected framework principles for microservices?
Observability (Logging, Monitoring, Tracing)
- What is observability in microservices?
- Difference between logging, monitoring, and tracing.
- How do you implement distributed tracing in microservices?
- What are common tools for monitoring microservices (Prometheus, Grafana, ELK)?
- Explain log aggregation in microservices.
- How do you implement correlation IDs for tracing requests?
- What is OpenTelemetry and its role in microservices?
- Difference between white-box and black-box monitoring.
- How do you monitor SLAs, SLOs, and SLIs in microservices?
- What is the role of health checks in microservices monitoring?
- How do you implement metrics collection in microservices?
- Explain anomaly detection in microservices logs.
- What is centralized logging and why is it important?
- How do you set up alerts and dashboards for microservices?
- What are common tracing tools (Jaeger, Zipkin)?
- Explain proactive vs reactive monitoring.
- What is log correlation in distributed systems?
- How do you monitor resource usage in Kubernetes microservices?
- What is synthetic monitoring?
- How do you perform root cause analysis in microservices failures?
Security in Microservices
- How do you secure microservices communication?
- What is OAuth2 and how is it used in microservices?
- Difference between OAuth2 and OpenID Connect.
- What is JWT and how is it used in authentication?
- How do you handle role-based access control in microservices?
- What is API security in microservices?
- How do you secure secrets in microservices?
- What is zero-trust security model?
- Explain mutual TLS (mTLS) in service-to-service communication.
- How do you protect microservices from DDoS attacks?
- What is rate limiting and how does it help in security?
- How do you handle multi-tenancy security in microservices?
- Explain token expiration and refresh in microservices authentication.
- What are common vulnerabilities in microservices?
- How do you implement API Gateway security policies?
- What is CORS and how do you handle it in microservices?
- How do you handle encryption at rest and in transit?
- Explain secrets rotation in microservices.
- What is penetration testing for microservices?
- How do you secure microservices running on Kubernetes?
CI/CD & DevOps for Microservices
- What is CI/CD in microservices?
- How do you design a CI/CD pipeline for microservices?
- What are the challenges of CI/CD in microservices?
- Explain blue-green deployment strategy.
- Explain canary release strategy.
- How do you implement feature toggles in microservices?
- What is progressive delivery?
- How do you handle rollback in microservices deployment?
- Explain GitOps for microservices deployment.
- What is infrastructure as code (IaC)?
- How do you use Terraform/CloudFormation for microservices?
- What is Helm and its role in Kubernetes deployments?
- How do you manage secrets in CI/CD pipeline?
- Explain automated testing in microservices CI/CD.
- What is chaos testing in CI/CD pipeline?
- How do you handle multi-service deployments?
- What is container registry and how is it used?
- Explain continuous monitoring in DevOps pipeline.
- What is service versioning in CI/CD?
- How do you handle database migrations in microservices CI/CD?
System Design & Real-World Scenarios
- How do you design an e-commerce platform with microservices?
- Design a payment service with fault tolerance.
- How do you design a notification service using microservices?
- Explain the design of an order management system.
- How do you design a logging and monitoring service?
- Design a microservices architecture for a video streaming platform.
- How do you handle data consistency in financial transactions?
- Design a search service with scalability in mind.
- How do you integrate legacy systems with microservices?
- How do you design for GDPR compliance in microservices?
- Explain design considerations for real-time chat service.
- How do you build an API Gateway for multiple services?
- Design a recommendation engine with microservices.
- How do you design a fault-tolerant authentication service?
- Explain architecture for microservices in a healthcare system.
- How do you handle schema evolution in real-world microservices?
- Design a scalable IoT platform with microservices.
- How do you ensure observability in a production-grade system?
- How do you design for multitenancy in SaaS microservices?
- What are trade-offs between synchronous and asynchronous designs in real-world systems?
Tricky & Advanced Questions
- What happens when a service in a saga fails?
- How do you debug issues in distributed transactions?
- Explain idempotency challenges in microservices.
- How do you detect and prevent cascading failures?
- What is distributed tracing overhead?
- How do you handle schema mismatch between services?
- Explain eventual consistency pitfalls in real-world systems.
- What is head-of-line blocking in message queues?
- How do you detect memory leaks in microservices?
- What is the impact of chatty APIs on performance?
- How do you prevent over-fetching and under-fetching in APIs?
- What are pitfalls of using shared libraries across microservices?
- How do you prevent dependency hell in microservices?
- Explain the impact of network latency in microservices.
- What are clock-skew issues in distributed systems?
- How do you test microservices locally with dependencies?
- Explain shadow traffic testing in microservices.
- What are sidecar patterns and their benefits?
- How do you migrate from monolith to microservices?
- What are best practices for API documentation in microservices?
Conclusion
🔥 This structured guide of 200+ professional, scenario-driven microservices interview questions spans across architecture, scalability, resilience, cloud (AWS), security, CI/CD, and real-world design. By preparing thoroughly with this masterlist, you will be equipped to tackle interviews for Senior Backend Engineer roles confidently in top companies.