Hello guys, If you are preparing for Java and Spring Boot Interview and looking for some Spring Cloud interview questions then you have come to the right place. Earlier, I have shared 15 Spring Boot Interview questions and today, I am going to share 15 Spring cloud interview questions for Java developers. These questions are good to revise essential Spring cloud concepts before interviews. Today is the world of cloud computing and most of the new Java development is happening on Cloud like AWS, GCP, and Azure. That's why it's very important for Java developers to learn about cloud and frameworks and libraries which support cloud-native development in Java, like Spring Cloud from Spring project. Spring is a powerful framework and probably the most popular Java framework. It is very popular and used widely throughout the world. Spring Cloud is a module provided by Spring that is used to develop cloud-based allocations. In simple words, Spring cloud provides Rapid Application Development (RAD) features to work with Spring. Because of its popularity and combination of Spring Boot and Spring Cloud for developing cloud-native Java applications and Microservices, you will find many Spring cloud-related questions on Java developer interviews. If you are preparing for a Java developer interview and your job requires knowledge of Spring Cloud and other Microservice technologies then it makes sense to spend some time learning Spring Cloud and getting yourself familiar with common and frequently asked questions. Spring Cloud is a bit complicated concept, especially for beginners. That is why there is a demand for experienced Spring cloud developers. But as mentioned, it is a complicated concept and interviews related to it have generally tough questions, hence it's better to join an online course like Master Microservices with Spring Boot and Spring Cloud course by Ranga Karnam from Udemy to learn essential Spring Boot and Spring Cloud concepts before going for interviews. 15 Best Spring Cloud Interview Questions with Answers In this article, I am going to share the top 15 questions related to Spring cloud for interviews. You can use these questions to not only prepare for the Spring Cloud interview but also to learn and explore essential Spring cloud concepts. Anyway, without wasting any more of your time, let's see popular Spring cloud questions for Java Interviews: 1. Explain Spring cloud? or, What is Spring Cloud? Answer: Spring cloud is a set of tools that can be used by developers to quickly build some common patterns in distributed systems and Microservices such as service discovery, configuration management, intelligent routing, circuit-breaker pattern etc. It's part of Spring Framework and also the most popular framework for building Microservice architecture in Java along with Spring Boot. 2. What are the common features of Spring cloud? Answer: Here is a list of some of the most common features of the Spring Cloud framework, which greatly help in developing cloud-native apps and Microservices in Java: a) Service registration and discovery b) Routing c) Service to service calls d) Distributed and versioned configuration e) load balancing and circuit breakers If you are interested to learn more about these spring cloud features then you can further see Spring Boot Microservices with Spring Cloud Beginner to Guru Udemy course by John Thompson, which provides a practical introduction to Spring Cloud for beginners. 3. Explain load balancing? or What is load balancing? Answer: Load balancing is a technique used to improve the distribution of workloads across several computing resources, such as a computer cluster, CPUs, network lines, and disk drives. In Microservice architecture, you can use API Gateway pattern to not just do load balancing but also implement authentication, authorization, and security. 4. How load balancing is implemented in the Spring cloud? Answer: you can implement load balancing in the Spring cloud using Netflix Ribbon, which is responsible for distributing the incoming request among the available instances of MIcroservices. Ribbon uses a round-robin algorithm by default to distribute the requests, but it also supports other load balancing algorithms, such as random and weighted load balancing. Ribbon is integrated with Spring Cloud's service registry, which means that it automatically discovers the available instances of a service and maintains a dynamic list of them. In addition to Ribbon, Spring Cloud also supports server-side load balancing using a component called "Zuul." Zuul acts as a gateway for incoming requests and routes them to the appropriate instance of a service based on various criteria, such as the request path and headers. 5. What is the meaning of Service registration and discovery? Answer: At the starting of a project, we usually have the entire configurations in the "properties" file. As the project proceeds and more services are developed and deployed, adding them to the properties file becomes complex. It can affect the already deployed services creating problems such as services going down or the location of some might change. Changing the properties manually can create more issues. Service registration and discovery are useful in such situations. The changes can be handled by service registration and discovery. 6. What is Hystrix? Answer: Hystrix is a fault-tolerance and latency library designed for isolating points of access to remote systems, third-party libraries, services, stopping cascading failures, and enabling resilience in complex distributed systems where failure is common and cannot be avoided. You can also use this to implement circuit-breaker pattern in Microservices. 7. Explain Netflix feign? Answer: Netflix Feign is a Java-based HTTP client that simplifies communication between microservices. It provides an easy-to-use declarative interface for making HTTP requests to other microservices. With Feign, developers can define interfaces for their REST APIs using annotations, and Feign will generate the implementation code automatically. This makes it easier to write and maintain code, and helps ensure consistency across the microservices. Feign also integrates with other Netflix technologies such as Ribbon and Eureka, which can help improve the reliability and resilience of microservices architectures. It is inspired by JAXRS-2.0, WebSocket, and Retrofit. 8. Why do we use Netflix feign? Answer: Netflix feign is used to reduce the complexity by binding denominator uniformly to HTTP APIs regardless of the RESTfulness. 9. What is the use of the Spring cloud bus? Answer: The spring cloud bus provides a helpful feature to refresh configurations across several multiple instances. 10. What are the advantages of Spring cloud? Answer: Here are key advantages of Spring Cloud a) Spring cloud helps in resolving complexity-associated issues with distributed systems. b) It provides service discovery which is a very helpful tool. c) It reduces redundancy. d) Load balancing is another helpful technique of Spring cloud. 11. What is PCF? Answer: PCF stands for Pivotal Cloud Foundry. It is an open-source, multi-platform cloud foundry. 12. What is the purpose of the Hystrix circuit breaker? Answer: The purpose of the Hystrix circuit breaker is to provide the first-page method or any other methods that the method on the first page might be calling and is causing the exception to recover. The chances of exception to recovery may increase because of less load. You can further see Master Microservices with Spring Boot and Spring Cloud course to learn more about Fault tolerance with Hysteric. 13. Name the services that provide service registration and discovery. Answer: Eureka and zookeeper are the two services which can provide service registration and discovery but they are not the only one. In Spring Cloud, the following services can be used for service registration and discovery: Eureka Consul ZooKeeper etcd Cloud Foundry Kubernetes 14. Give the benefits of Eureka and Zookeeper? Answer: Eureka guarantees high availability and usability while Zookeeper guarantees consistency and partition fault tolerance. 15. What is the major difference between Spring Cloud and Spring boot? (Answer) Answer: Spring Boot and Spring Cloud are two different frameworks in the Spring ecosystem. Spring Boot is a Java framework that simplifies the development of stand-alone, production-grade Spring-based applications. It offers several features such as auto-configuration, starter dependencies, and a simplified development experience. On the other hand, Spring Cloud is a framework that is used to build distributed systems and microservices-based applications. It provides several components that can help developers to develop, deploy, and manage distributed systems. These components include service discovery, circuit breaker, configuration management, API gateway, and distributed tracing. In summary, the major difference between Spring Boot and Spring Cloud is that Spring Boot is a framework for developing stand-alone, production-grade Spring-based applications, while Spring Cloud is a framework for building distributed systems and microservices-based applications Spring cloud is a microservice management and coordination framework used to integrate and manage individual microservices while Spring boot is used to develop these microservices. 16. What are some common Spring cloud annotations? (answer) Answer: here is a list of some of the most essential Spring cloud annotations for Java developers @EnableConfigServer @EunableEurekaServer @EnableDiscoveryClient @EnableCircuitBreaker @HystricCommand You can further see the answer for a detailed explanation of these Spring cloud annotations with examples. 17. What is difference between Ribbon and Zuul in Spring Cloud Framework?While both Ribbon and Zuul are components of the Spring Cloud framework that facilitate the development of microservices-based architectures. However, they serve different purposes: Ribbon is a client-side load balancer that enables a client to distribute requests across multiple service instances. It is a core component of the Spring Cloud Netflix stack. Zuul, on the other hand, is a server-side load balancer that acts as a gateway for all the client requests. It enables intelligent routing, filtering, and monitoring of the requests to the backend services. It is a part of the Spring Cloud Netflix stack.In summary, while Ribbon is focused on load balancing between client and server, Zuul is focused on managing the client requests to the backend services.This is also one of the popular spring cloud question which I have seen more and more on recent days. 18. What is difference between API Gateway and Load Balancer? (Answer) This is another popular Microservie question for Java developers because both are quite similar. For example, API Gateway and Load Balancer are both important components of a distributed system, but they serve different purposes. A Load Balancer is responsible for distributing incoming network traffic across multiple servers to ensure that no single server is overwhelmed. It helps to improve system availability, scalability, and reliability. On the other hand, an API Gateway acts as a reverse proxy for the microservices and acts as a single entry point for clients. It provides a unified interface for clients to interact with multiple microservices. The API Gateway handles tasks like request routing, authentication, and API versioning. It also helps to improve the security, scalability, and maintainability of a system. In summary, while Load Balancer distributes traffic across multiple servers, API Gateway acts as a single entry point for clients and provides a unified interface to interact with multiple microservices. That's all about the frequently asked Spring Cloud Interview Questions for Java and Spring Developers. You can revise these Spring Cloud questions before attending any Java and Spring framework interview. As I said, Spring cloud is complex, especially for beginners, hence it's also a good idea to spend some time learning Spring cloud itself. If you need resources, here are some highly recommended this course from Udemy and Pluralsight. 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(courses) 3 Best Practices Java Programmers can learn from Spring (best practices) Thanks for reading this article so far. If you found these Spring Cloud Interview questions useful then please share them with your colleagues and friends. If you have any questions or feedback then please drop a note. P. S. - If you want to learn about Microservices, Spring Cloud, and Java development but looking for free resources to start with then Developing Cloud-Native Apps with Microservices Architecture, an official free Redhat training course on Udemy is worth looking at. The course is completely free, all you need is a Udemy account to enroll in this course. P. S. S. - If you think 15 questions is not enough then you may want to know that I am also writing a book on Grokking the Spring Boot interview where I will share more questions. You can join my list for early access and updates.