Microservices Fundamentals: Essential Interview Questions Quiz

Test your understanding of core microservices architecture concepts with this beginner-level quiz, designed to help you prepare for interviews. Assess your knowledge on message delivery, service independence, scalability, and patterns frequently encountered in microservices design.

1. Idempotency in Microservices

   Why is idempotency important for consumers in microservices systems when processing messages, such as in an Order Service?

   1. It helps microservices run without using any messages.
   2. It ensures that all consumers use the same programming language.
   3. It speeds up the delivery of all messages across services.
   4. It prevents duplicate processing if the same message is received more than once.

   Explanation: Idempotency ensures that repeating the same operation with the same input will not have additional effects, preventing issues from processing duplicates. Speeding up delivery (option B) is not a direct effect of idempotency. Service language uniformity (option C) and running without messages (option D) are unrelated to idempotency.

2. Message Delivery: Exactly-Once Semantics

   When using a messaging system between Payment Service and Order Service, which strategy helps achieve exactly-once message delivery?

   1. Disable all transactions for faster delivery.
   2. Send each message twice to be sure it arrives.
   3. Rely solely on at-least-once delivery guarantees.
   4. Enable transactional messaging and use idempotent consumers.

   Explanation: Transactional messaging combined with idempotent consumers can prevent duplicate processing and ensure exactly-once delivery. Sending messages twice (option C) risks duplication, and relying on at-least-once (option D) or disabling transactions (option B) does not guarantee exactly-once delivery.

3. Service Independence

   How do microservices architectures ensure that each service can be developed, deployed, and scaled independently?

   1. By combining all services into one deployable unit.
   2. By making all services depend on one central service.
   3. By keeping the codebase and data storage separate for each service.
   4. By using a single shared database for all services.

   Explanation: Independence is achieved when each service maintains its own code and data, enabling separation of concerns. Sharing a database (option B), combining services (option C), or making services dependent (option D) contradicts the principles of microservices.

4. Scaling Microservices

   What is a primary advantage of scaling microservices compared to monolithic applications?

   1. The entire application must be taken offline to scale.
   2. All services are forced to use the same technology stack.
   3. Scaling is not possible in microservices architectures.
   4. Only the needed services are scaled, not the entire system.

   Explanation: Microservices allow selective scaling, such as increasing instances for a high-traffic service, without affecting others. Monoliths (option B) often require scaling the whole app, and microservices can use diverse technologies (contradicting option C). Option D is incorrect, as scaling is a key feature.

5. Database Per Service Pattern

   Why is the 'database per service' pattern often recommended in microservices?

   1. It forces all services to share the same database schema.
   2. It allows each service to manage its own data without tight coupling.
   3. It makes all services use the same data model.
   4. It eliminates the need for any databases.

   Explanation: Having a separate database for each service supports autonomy and avoids tight coupling. Sharing schemas (option B) or data models (option D) increases interdependency, and eliminating databases (option C) is impractical.

6. Service Discovery

   Which mechanism helps microservices dynamically locate each other without hardcoded network addresses?

   1. Service discovery
   2. Code duplication
   3. Database indexing
   4. Manual IP configuration

   Explanation: Service discovery allows automatic detection of service network locations, promoting flexibility. Manual configuration (option B) is error-prone, database indexing (option C) is unrelated, and code duplication (option D) does not address service communication.

7. API Gateway Role

   What is the main purpose of an API Gateway in microservices architecture?

   1. To automatically deploy all services without configuration.
   2. To provide a single entry point for client requests and route them to the appropriate services.
   3. To store all the data for each service centrally.
   4. To enforce coding standards across all teams.

   Explanation: An API Gateway acts as a unified interface, directing traffic to various microservices. It does not store data (option B), enforce code standards (option C), or handle deployments (option D).

8. Handling Service Failures

   Which lightweight resilience pattern can microservices use to avoid overloading when a dependent service is down?

   1. Version control
   2. Database sharding
   3. Daily backups
   4. Circuit breaker

   Explanation: A circuit breaker pattern helps services quickly fail when a dependency is unresponsive, preventing overload. Backups (option B), sharding (option C), and version control (option D) are important but do not provide runtime resilience between services.

9. REST in Microservices

   What is one common benefit of using REST APIs for inter-service communication in microservices?

   1. They guarantee faster network speed for all calls.
   2. They force services to use a shared database.
   3. They provide a simple and widely understood communication protocol.
   4. They require all services to be written in the same language.

   Explanation: REST APIs are language-agnostic and promote broad compatibility due to their simplicity. REST does not enforce languages (option B), databases (option C), or network speeds (option D).

10. Statelessness Principle

    Why is statelessness considered important for microservices handling requests?

    1. It requires all requests to be saved on disk immediately.
    2. It prevents services from communicating with each other.
    3. It ensures each request is handled independently, making horizontal scaling easier.
    4. It allows storing user session data directly inside the service.

    Explanation: Stateless services independently process requests, simplifying load balancing and scaling. Options B and D misunderstand statelessness, while option C wrongly claims services cannot communicate—they do, but do not store client session state.