Spring Boot & Microservices Questions Interview Questions and Answers
Practice every question in this topic using expandable answers and interview tips. Answer aloud first, then open the explanation.
Back to the complete interview hub
Q1. What is Spring Boot and why is it preferred over Spring Framework? [Easy]
Answer: Spring Boot is an extension of the Spring Framework designed to simplify Java enterprise application development. It offers auto-configuration, standalone embedded Tomcat/Jetty servers, starter dependencies, and production-ready features without requiring complex XML configuration files.
Interview tip: Define it clearly, give a small example, and mention one practical use or limitation.
Q2. What does the @SpringBootApplication annotation do? [Easy]
Answer: @SpringBootApplication is a composite annotation that combines three key Spring annotations: @SpringBootConfiguration (marks the class as configuration source), @EnableAutoConfiguration (enables automatic Spring bean configuration), and @ComponentScan (scans the package for components like @Controller, @Service, and @Repository).
Interview tip: Define it clearly, give a small example, and mention one practical use or limitation.
Q3. What is Dependency Injection (DI) and Inversion of Control (IoC) in Spring? [Easy]
Answer: Inversion of Control (IoC) is a design principle where the object creation and lifecycle management are delegated to the Spring IoC Container. Dependency Injection (DI) is the pattern used to inject required bean dependencies into a class using constructors, setters, or @Autowired fields.
Interview tip: Define it clearly, give a small example, and mention one practical use or limitation.
Q4. What is the difference between @RestController and @Controller in Spring Boot? [Medium]
Answer: @Controller is used for traditional Spring MVC web controllers that return views (like JSP/Thymeleaf templates). @RestController is a convenient annotation combining @Controller and @ResponseBody, returning serialized JSON/XML responses directly in the HTTP body, ideal for RESTful web services.
Interview tip: Define it clearly, give a small example, and mention one practical use or limitation.
Q5. Explain Spring Data JPA and Hibernate ORM. [Medium]
Answer: Hibernate is an Object-Relational Mapping (ORM) framework that maps Java domain classes to relational database tables. Spring Data JPA is an abstraction layer built on top of JPA/Hibernate that dramatically reduces boilerplate database code by providing built-in CRUD operations via interfaces like JpaRepository.
Interview tip: Define it clearly, give a small example, and mention one practical use or limitation.
Q6. How do Spring Boot Microservices communicate with each other? [Medium]
Answer: Microservices communicate synchronously using REST APIs (via RestTemplate, WebClient, or Spring Cloud OpenFeign) or asynchronously using message brokers like Apache Kafka, RabbitMQ, or ActiveMQ.
Interview tip: Define it clearly, give a small example, and mention one practical use or limitation.
Q7. What is Spring Cloud API Gateway and Service Discovery (Eureka)? [Hard]
Answer: Eureka is a Service Discovery registry where microservices dynamically register their instance instances. Spring Cloud API Gateway acts as a single entry point for client requests, handling routing, rate limiting, authentication, load balancing, and cross-cutting security concerns.
Interview tip: Define it clearly, give a small example, and mention one practical use or limitation.
Q8. How do you handle distributed transactions in Microservices using the Saga Pattern? [Hard]
Answer: In microservices architecture, traditional two-phase commit (2PC) is inefficient. The Saga pattern breaks a distributed transaction into a series of local transactions. If a step fails, compensation transactions are executed in reverse to undo changes. Sagas can be Choreography-based (event driven) or Orchestration-based (central orchestrator).
Interview tip: Define it clearly, give a small example, and mention one practical use or limitation.
Study checklist
- Explain the answer without reading.
- Write one small example.
- Compare framework or database version differences in official documentation.
Spring Boot & Microservices Questions Interview Questions and Answers
Practice one question at a time. Read the question, answer aloud, then compare your explanation with the answer.
← Back to the complete interview hub
Q1. What is Spring Boot and why is it preferred over Spring Framework?
Easy
Answer: Spring Boot is an extension of the Spring Framework designed to simplify Java enterprise application development. It offers auto-configuration, standalone embedded Tomcat/Jetty servers, starter dependencies, and production-ready features without requiring complex XML configuration files.
Interview tip: Use a short example and connect the answer to real project work.
Q2. What does the @SpringBootApplication annotation do?
Easy
Answer: @SpringBootApplication is a composite annotation that combines three key Spring annotations: @SpringBootConfiguration (marks the class as configuration source), @EnableAutoConfiguration (enables automatic Spring bean configuration), and @ComponentScan (scans the package for components like @Controller, @Service, and @Repository).
Interview tip: Use a short example and connect the answer to real project work.
Q3. What is Dependency Injection (DI) and Inversion of Control (IoC) in Spring?
Easy
Answer: Inversion of Control (IoC) is a design principle where the object creation and lifecycle management are delegated to the Spring IoC Container. Dependency Injection (DI) is the pattern used to inject required bean dependencies into a class using constructors, setters, or @Autowired fields.
Interview tip: Use a short example and connect the answer to real project work.
Q4. What is the difference between @RestController and @Controller in Spring Boot?
Medium
Answer: @Controller is used for traditional Spring MVC web controllers that return views (like JSP/Thymeleaf templates). @RestController is a convenient annotation combining @Controller and @ResponseBody, returning serialized JSON/XML responses directly in the HTTP body, ideal for RESTful web services.
Interview tip: Use a short example and connect the answer to real project work.
Q5. Explain Spring Data JPA and Hibernate ORM.
Medium
Answer: Hibernate is an Object-Relational Mapping (ORM) framework that maps Java domain classes to relational database tables. Spring Data JPA is an abstraction layer built on top of JPA/Hibernate that dramatically reduces boilerplate database code by providing built-in CRUD operations via interfaces like JpaRepository.
Interview tip: Use a short example and connect the answer to real project work.
Q6. How do Spring Boot Microservices communicate with each other?
Medium
Answer: Microservices communicate synchronously using REST APIs (via RestTemplate, WebClient, or Spring Cloud OpenFeign) or asynchronously using message brokers like Apache Kafka, RabbitMQ, or ActiveMQ.
Interview tip: Use a short example and connect the answer to real project work.
Q7. What is Spring Cloud API Gateway and Service Discovery (Eureka)?
Hard
Answer: Eureka is a Service Discovery registry where microservices dynamically register their instance instances. Spring Cloud API Gateway acts as a single entry point for client requests, handling routing, rate limiting, authentication, load balancing, and cross-cutting security concerns.
Interview tip: Use a short example and connect the answer to real project work.
Q8. How do you handle distributed transactions in Microservices using the Saga Pattern?
Hard
Answer: In microservices architecture, traditional two-phase commit (2PC) is inefficient. The Saga pattern breaks a distributed transaction into a series of local transactions. If a step fails, compensation transactions are executed in reverse to undo changes. Sagas can be Choreography-based (event driven) or Orchestration-based (central orchestrator).
Interview tip: Use a short example and connect the answer to real project work.
Quick revision checklist
- Explain the answer without reading.
- Write one small example.
- Review platform or version differences in official documentation.
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