Last Updated on June 29th, 2024

If you are a Java developer, you are expected to have a good understanding of Microservices Concepts, both conceptual part & programming part as well. Undoubtedly, Microservices is the demanding programming pattern in the industry. Spring Boot & Spring Cloud support to develop Microservices based applications in Java. If you have a good hold on both, you will easily be able to work on it smoothly. In this article, we will refresh the Microservices concepts in the form of MCQs that are frequently asked in the interviews as well. Furthermore, you must also get benefitted in both either a written test or the interviews from these Java Microservices MCQs.

Here are the most important and foundation based multiple-choice questions (MCQs) on the topic “Java Microservices MCQ Questions & Answers Explained” including some code-based questions, with answers and detailed explanations:

Java Microservices MCQ Questions & Answers Explained

What is a microservice?

A) A small application that runs on a single machine
B) A design pattern used in monolithic applications
C) An architectural style that structures an application as a collection of loosely coupled services
D) A cloud-based service for micro-managing resources

Answer: C

Explanation: A microservice is an architectural style that structures an application as a collection of loosely coupled services, which implement business capabilities.

Which of the following is NOT a characteristic of microservices?

A) Small and focused on a single responsibility
B) Centralized database for all services
C) Independent deployability
D) Inter-Service Communication

Answer: B

Explanation: Microservices typically have decentralized data management, where each service manages its own database, promoting independence and resilience.

What is one of the primary roles of Spring Boot in microservices development?

A) To provide a large monolithic application framework.
B) To enforce a specific technology stack for all microservices.
C) To manage database transactions across all services.
D) To simplify the configuration and deployment of microservices.

Answer: D

Explanation: Spring Boot simplifies the configuration and deployment of microservices by providing a set of pre-configured templates and reducing the amount of boilerplate code required.

How does an API Gateway contribute to security in a microservices architecture?

A) By embedding security code within each microservice.
B) By managing authentication and authorization for incoming requests.
C) By storing and managing user data directly.
D) By eliminating the need for secure communication protocols.

Answer: B

Explanation: An API Gateway contributes to security by managing authentication and authorization for incoming requests. It can enforce security policies and ensure that only authenticated and authorized requests reach the microservices.

How does a Service Registry assist communication in a microservices architecture?

A) By hardcoding the addresses of each service into the client.
B) By providing a central directory where services can register and discover each other dynamically.
C) By directly managing the communication protocols between services.
D) By storing and managing user session data.

Answer: B

Explanation: A Service Registry facilitates communication by providing a central directory where services can register and discover each other dynamically. This enables services to find and interact with each other without needing hardcoded addresses.

In a Spring Boot microservices architecture, which of the following tools can be used as an alternative to Netflix Eureka for service discovery?

A) Spring Data JPA
B) Spring Cloud Config
C) Consul
D) RabbitMQ

Answer: C

Explanation: Consul can be used as an alternative to Netflix Eureka for service discovery in a Spring Boot microservices architecture. It provides service discovery, health checking, and a key-value store, among other features.

What is the primary purpose of an API Gateway in microservices?

A) To directly manage databases for all microservices.
B) To act as a single entry point for client requests to multiple microservices.
C) To enforce security policies within each microservice.
D) To replace the need for inter-service communication.

Answer: B

Explanation: An API Gateway acts as a single entry point for client requests to multiple microservices. It handles request routing, composition, and protocol translation, simplifying client interactions with the system.

What makes HTTP/HTTPS a suitable protocol for microservices communication?

A) Its ability to transfer large files quickly
B) Its native support for real-time communication
C) Its widespread use and support for RESTful APIs
D) Its built-in messaging queue capabilities

Answer: C

Explanation: HTTP/HTTPS is suitable for microservices communication because of its widespread use and support for RESTful APIs. This allows microservices to communicate in a standardized and stateless manner.

In microservices architecture, what is meant by ‘polyglot persistence’?

A) Using multiple databases within a single service
B) Using the same database technology across all services
C) Using different database technologies for different services based on their needs
D) Using multiple programming languages within a single service

Answer: C

Explanation: Polyglot persistence refers to using different database technologies for different services based on their specific requirements and characteristics.

What is Circuit Breaker pattern used for in microservices?

A) To manage database transactions
B) To handle failed requests between microservices gracefully
C) To increase service discovery efficiency
D) To ensure data consistency across services

Answer: B

Explanation: The Circuit Breaker pattern is used to detect and handle failed requests between microservices, preventing cascading failures and providing fallback mechanisms.

Which principle states that each microservice should have its own database?

A) Single Responsibility Principle
B) Database Isolation Principle
C) Decentralized Data Management
D) Data Consistency Principle

Answer: C

Explanation: The principle of Decentralized Data Management states that each microservice should manage its own database, promoting independence and resilience.

What is a common way to handle inter-service communication in a microservices architecture?

A) Monolithic APIs
B) SOAP web services
C) RESTful APIs
D) Batch processing

Answer: C

Explanation: RESTful APIs are a common way to handle inter-service communication in microservices, providing a standardized, stateless interface for services to interact.

What is the main advantage of using Docker with microservices?

A) Enhanced performance
B) Simplified scaling and deployment
C) Increased security
D) Easier coding

Answer: B

Explanation: Docker simplifies scaling and deployment by allowing microservices to be packaged into containers, ensuring consistency across different environments. For more details, kindly go through Why is Docker used?.

Which tool can be used for monitoring and managing microservices?

A) JUnit
B) Jenkins
C) Prometheus
D) Maven

Answer: C

Explanation: Prometheus is a tool used for monitoring and managing microservices, providing metrics collection, querying, and alerting capabilities.

What does the term ‘event-driven architecture’ refer to in microservices?

A) Using API calls to manage service dependencies
B) Using scheduled tasks to manage microservices
C) Using database triggers to handle updates
D) Using events to trigger changes in the system

Answer: D

Explanation: Event-driven architecture in microservices refers to using events to trigger changes in the system, promoting decoupling and asynchronous communication between services.

Which of the following is a benefit of using Spring Cloud Config for microservices?

A) Centralized configuration management
B) Enhanced database transaction handling
C) Improved user interface design
D) Faster development cycles

Answer: A

Explanation: Spring Cloud Config provides centralized configuration management, allowing for external configuration of microservices across different environments.

What is the purpose of Hystrix in a Spring Boot microservices application?

A) To manage database connections
B) To provide service discovery
C) To implement the Circuit Breaker pattern
D) To handle authentication

Answer: C

Explanation: Hystrix is used to implement the Circuit Breaker pattern in a Spring Boot microservices application, helping to manage failures and provide fallback mechanisms.

Which design pattern is commonly used to manage the lifecycle of microservices?

A) Singleton Pattern
B) Factory Pattern
C) Observer Pattern
D) Orchestration Pattern

Answer: D

Explanation: The Orchestration Pattern is commonly used to manage the lifecycle of microservices, coordinating the execution of different services to achieve a business goal.

What is the role of Spring Cloud Sleuth & Zipkin in microservices?

A) To provide security for microservices
B) To handle database transactions
C) To enable distributed tracing and logging
D) To manage service deployment

Answer: C

Explanation: Spring Cloud Sleuth provides distributed tracing and logging, helping to track requests across multiple microservices for debugging and monitoring purposes.

What is the primary purpose of using Spring Boot Actuator in microservices?

A) To enhance security
B) To provide production-ready features like monitoring and health checks
C) To improve database performance
D) To simplify user authentication

Answer: B

Explanation: Spring Boot Actuator provides production-ready features such as monitoring, metrics, and health checks, helping to manage and monitor microservices in a production environment.

Given the following Spring Boot application, what annotation is used to enable Eureka client functionality?

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
public class EurekaClientApplication {
   public static void main(String[] args) {
      SpringApplication.run(EurekaClientApplication.class, args);
   }
}

A) @EnableEurekaClient
B) @EnableDiscoveryClient
C) @EnableFeignClients
D) @EnableConfigServer

Answer: A

Explanation: The @EnableEurekaClient annotation is used to enable Eureka client functionality in a Spring Boot application, allowing it to register with a Eureka server.

In the context of Spring Cloud Config, what is the purpose of the @EnableConfigServer annotation?

A) To enable Eureka client functionality
B) To enable Spring Cloud Config Server functionality
C) To enable distributed tracing
D) To enable API Gateway functionality

Answer: B

Explanation: The @EnableConfigServer annotation is used to enable Spring Cloud Config Server functionality, allowing the application to serve configuration properties to other microservices.

What does the following code snippet demonstrate in a Spring Boot microservices application?

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class ServiceAController {
    private final RestTemplate restTemplate;

    public ServiceAController(RestTemplate restTemplate) {
       this.restTemplate = restTemplate;
    }

    @GetMapping("/serviceA")
    public String callServiceB() {
       String serviceBResponse = restTemplate.getForObject("http://service-b/serviceB", String.class);
       return "Response from Service B: " + serviceBResponse;
    }
}

A) Synchronous communication between services using RestTemplate
B) Asynchronous communication between services using RestTemplate
C) Inter-service communication using message queues
D) Database access using JPA

Answer: A

Explanation: This code demonstrates synchronous communication between services using RestTemplate, where Service A calls an endpoint of Service B and processes the response.

What is the purpose of the following application.properties configuration in a Spring Boot application?

spring.application.name=service-a
eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

A) To configure the database connection and API endpoints
B) To set up application logging and error handling
C) To enable the application to register with Eureka for service discovery
D) To define security settings and authentication protocols

Answer: C

Explanation: The combined purpose of these properties is to enable the application to register with the Eureka server for service discovery. “spring.application.name=service-a” sets the application name, and “eureka.client.service-url.defaultZone=http://localhost:8761/eureka/” provides the URL of the Eureka server where the application registers itself and can discover other services.

What does the following Spring Boot configuration class do?

import org.springframework.cloud.netflix.zuul.EnableZuulProxy;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableZuulProxy
public class ApiGatewayConfiguration {
}
...

A) Configures a database connection
B) Enables Eureka client functionality
C) Configures an API Gateway using Zuul
D) Sets up distributed tracing

Answer: C

Explanation: This configuration class enables Zuul proxy functionality, setting up an API Gateway that can route requests to various microservices.

What is the purpose of the @FeignClient annotation in a Spring Boot application?

A) To enable Eureka client functionality
B) To declare a REST client that uses Feign
C) To enable distributed tracing
D) To configure a database connection

Answer: B

Explanation: The @FeignClient annotation is used to declare a REST client that uses Feign, which simplifies HTTP communication between microservices by providing a declarative approach. For further details, please go through ‘How to implement Feign Client in Spring boot Microservices?‘.

Given the following Feign client interface, what does it do?

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

@FeignClient(name = "service-b")
public interface ServiceBClient {
    
    @GetMapping("/serviceB")
    String getServiceBResponse();
}
```

A) Defines a REST client for interacting with Service B
B) Configures a database connection for Service B
C) Sets up distributed tracing for Service B
D) Enables service registration for Service B

Answer: A

Explanation: This interface defines a REST client for interacting with Service B, using Feign to simplify the HTTP communication.

Which of the following features is a key benefit of using Spring Cloud Gateway in a microservices architecture?

A) Decentralized configuration management
B) Integrated development environment
C) Dynamic routing and load balancing
D) Built-in messaging queue

Answer: C

Explanation: A key benefit of using Spring Cloud Gateway is dynamic routing and load balancing. It can route requests to the appropriate microservices based on various criteria and balance the load among multiple instances of a service, improving reliability and performance.

Which design pattern is commonly used for handling data consistency in microservices?

A) Singleton Pattern
B) Saga Pattern
C) Factory Pattern
D) Proxy Pattern

Answer: B

Explanation: The Saga Pattern is commonly used for handling data consistency in microservices, coordinating distributed transactions by breaking them into smaller, manageable steps.

What does the following Spring Boot configuration class demonstrate?

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class AppConfig {
   @Bean
   public RestTemplate restTemplate() {
      return new RestTemplate();
   }
}

A) Configuration of a data source
B) Creation of a RestTemplate bean for inter-service communication
C) Configuration of an API Gateway
D) Setup of a distributed tracing tool

Answer: B

Explanation: This configuration class creates a RestTemplate bean, which can be used for synchronous inter-service communication within a Spring Boot application.

Which of the following tools can be used for container orchestration in a microservices architecture?

A) Docker Compose
B) Kubernetes
C) JUnit
D) Maven

Answer: B

Explanation: Kubernetes is a tool used for container orchestration, managing the deployment, scaling, and operation of containerized applications in a microservices architecture.

What is the purpose of the @LoadBalanced annotation in Spring Boot?

A) To enable distributed tracing
B) To configure a RestTemplate bean for client-side load balancing
C) To manage database transactions
D) To set up an API Gateway

Answer: B

Explanation: The @LoadBalanced annotation is used to configure a RestTemplate bean for client-side load balancing, distributing requests across multiple instances of a service.

In Spring Cloud, what is the purpose of using a Config Server?

A) To handle user authentication
B) To manage database connections
C) To provide externalized configuration for microservices
D) To monitor application performance

Answer: C

Explanation: A Config Server in Spring Cloud provides externalized configuration for microservices, allowing them to retrieve their configuration properties from a central server.

Which of the following best describes the purpose of the Sidecar Pattern in microservices?

A) To enhance user interface design
B) To manage database connections
C) To offload common functionalities like logging and monitoring from the main service
D) To handle distributed transactions

Answer: C

Explanation: The Sidecar Pattern offloads common functionalities like logging, monitoring, and configuration from the main service to a separate sidecar container, promoting separation of concerns.

What is the benefit of using Docker in a microservices architecture?

A) Simplified user interface design
B) Enhanced security
C) Consistent deployment environments
D) Improved data consistency

Answer: C

Explanation: Docker provides consistent deployment environments by packaging applications and their dependencies into containers, ensuring they run the same way across different environments.

What does the below instruction do in the Dockerfile?

ADD target/myapp.jar myapp.jar

A) It sets the main class for the Java application.
B) It adds the application JAR file from the ‘target’ directory on the host to the container and renames it to ‘myapp.jar’.
C) It sets environment variables for the Docker container.
D) It installs dependencies required by the Java application.

Answer: B

Explanation: The ‘ADD target/myapp.jar myapp.jar’ instruction adds the application JAR file from the target directory on the host to the Docker container and renames it to myapp.jar.

Which of the following tools can be used for monitoring and visualizing metrics in a Spring Boot microservices architecture?

A) Jenkins
B) Prometheus and Grafana
C) JUnit
D) Hibernate

Answer: B

Explanation: Prometheus is used for collecting metrics, and Grafana is used for visualizing those metrics, making them a common combination for monitoring and visualizing metrics in a Spring Boot microservices architecture.

Which of the following is NOT a typical function of an API Gateway in a microservices architecture?

A) Load balancing
B) Service discovery
C) Centralized logging and monitoring
D) Direct database access for all microservices

Answer: D

Explanation: Direct database access for all microservices is not a typical function of an API Gateway. Instead, the API Gateway handles request routing, load balancing, service discovery, and centralized logging and monitoring, among other functions.

Which of the following is NOT a role of a Service Registry in a microservices architecture?

A) Ensuring high availability of service instances through health checks.
B) Storing business logic for individual services.
C) Enabling load balancing by providing service instance details to clients.
D) Allowing services to dynamically discover and communicate with each other.

Answer: B

Explanation: Storing business logic for individual services is not a role of a Service Registry. Instead, a Service Registry ensures high availability through health checks, enables load balancing, and allows services to dynamically discover and communicate with each other.

Which tool is commonly used for service registration and discovery in a Spring Boot microservices architecture?

A) Apache Kafka
B) Netflix Eureka
C) Jenkins
D) Prometheus

Answer: B

Explanation: Netflix Eureka is commonly used for service registration and discovery in a Spring Boot microservices architecture. It allows microservices to register themselves and to discover other registered services.

What is the primary purpose of Netflix Eureka in a Spring Boot microservices setup?

A) To provide logging and monitoring services
B) To manage build and deployment pipelines
C) To register and discover services dynamically
D) To handle message queuing and processing

Answer: C

Explanation: The primary purpose of Netflix Eureka in a Spring Boot microservices setup is to register and discover services dynamically. This allows services to find and communicate with each other without hardcoding their network locations.

What is the primary purpose of using Resilience4j in a microservices architecture?

A) To enable centralized and version-controlled configuration updates
B) To provide resilience and fault-tolerance mechanisms for microservices
C) To trace and monitor requests across multiple services
D) To register microservices with Eureka server

Answer: B

Explanation: The primary purpose of using Resilience4j in a microservices architecture is to provide resilience and fault-tolerance mechanisms. It helps to handle failures gracefully and improve the stability and reliability of the system.

Which of the following features is NOT provided by Resilience4j?

A) Circuit Breaker
B) Rate Limiter
C) Retry
D) Data Encryption

Answer: D

Explanation: Resilience4j provides several resilience features such as Circuit Breaker, Rate Limiter, Time Limiter, Bulkhead, and Retry. However, Data Encryption is not one of the features provided by Resilience4j.

Besides HTTP/HTTPS, which other protocol is commonly used for microservices communication, especially for high performance and low latency?

A) SOAP
B) FTP
C) gRPC
D) IMAP

Answer: C

Explanation: gRPC is another protocol commonly used for microservices communication, especially for high performance and low latency scenarios. It uses HTTP/2 for transport, supports multiple languages, and provides efficient binary serialization.

How does Spring Cloud Config enhance the deployment process in a microservices architecture?

A) By providing automated UI design tools
B) By enabling centralized and version-controlled configuration updates
C) By offering built-in analytics and reporting
D) By embedding a web server within each microservice

Answer: B

Explanation: Spring Cloud Config enhances the deployment process by enabling centralized and version-controlled configuration updates. This allows you to manage and update configurations across all services seamlessly, improving deployment efficiency and reducing the risk of inconsistencies.

What is the primary role of Spring Cloud Gateway in a microservices architecture?

A) To provide a single entry point for client requests and route them to the appropriate services
B) To handle database connections
C) To manage user authentication
D) To perform background processing tasks

Answer: A

Explanation: Spring Cloud Gateway provides a single entry point for client requests, routing them to the appropriate microservices and handling cross-cutting concerns like security and rate limiting.

In a microservices architecture, what is the benefit of using a distributed tracing tool like Zipkin?

A) To improve database performance
B) To enhance user interface design
C) To trace and monitor requests across multiple services
D) To manage user authentication

Answer: C

Explanation: Distributed tracing tools like Zipkin trace and monitor requests across multiple services, helping to debug issues and understand the flow of requests through the system.