Software Architecture, Design Patterns, SDLC, and Software Development Interview Questions

 

Table of Contents

1. Beginner-Level Questions

   • Software Architecture

   • Design Patterns

   • SDLC

   • Software Development

2. Intermediate-Level Questions

   • Software Architecture

   • Design Patterns

   • SDLC

   • Software Development

3. Expert-Level Questions

   • Software Architecture

   • Design Patterns

   • SDLC

   • Software Development

4. Conclusion

---

Beginner-Level Questions

These questions focus on foundational concepts, basic coding, and understanding core principles across Software Architecture, Design Patterns, SDLC, and Software Development.

Software Architecture (Beginner)

1. What is Software Architecture, and why is it important?

   • Type: Basic Understanding

   • Expected Answer: Software Architecture defines the high-level structure of a system, outlining components, their interactions, and design principles. It ensures scalability, maintainability, and performance.

   • Example: A web app with a frontend, backend, and database layers, where architecture ensures clear separation of concerns.

2. What are the key components of a software system architecture?

   • Type: Conceptual

   • Expected Answer: Components include modules, interfaces, data flow, and deployment structures, designed to meet functional and non-functional requirements.

3. What is the difference between monolithic and microservices architecture?

   • Type: Conceptual

   • Expected Answer: Monolithic architecture is a single, unified application, while microservices split functionality into independent services communicating via APIs.

4. What is a client-server architecture?

   • Type: Basic Understanding

   • Expected Answer: A client-server architecture divides tasks between clients (requesting services) and servers (providing services), like a web browser and server.

5. What is the role of a software architect?

   • Type: Conceptual

   • Expected Answer: A software architect designs the system’s structure, makes high-level design decisions, and ensures technical alignment with business goals.

6. How does layering work in software architecture?

   • Type: Conceptual

   • Expected Answer: Layering organizes a system into layers (e.g., presentation, business, data) with defined responsibilities to improve modularity.

   • Example: A 3-tier architecture with UI, logic, and database layers.

7. What is scalability in software architecture?

   • Type: Basic Understanding

   • Expected Answer: Scalability is the ability of a system to handle increased load by adding resources (horizontal or vertical scaling).

8. What is the purpose of an architectural diagram?

   • Type: Practical

   • Expected Answer: Architectural diagrams visualize system components, relationships, and data flow for communication and planning.

9. What is a RESTful architecture?

   • Type: Conceptual

   • Expected Answer: REST (Representational State Transfer) is an architectural style using HTTP methods for stateless, scalable communication.

   • Example: A REST API fetching user data via GET /users.

10. What is the difference between architecture and design?

    • Type: Conceptual

    • Expected Answer: Architecture focuses on high-level structure, while design focuses on detailed implementation within components.

Design Patterns (Beginner)

11. What is a design pattern, and why is it used?

    • Type: Basic Understanding

    • Expected Answer: Design patterns are reusable solutions to common software problems, reducing complexity and improving maintainability.

    • Example: Singleton pattern ensures a single instance of a class.

12. What are the three main categories of design patterns?

    • Type: Conceptual

    • Expected Answer: Creational (object creation), Structural (object composition), and Behavioral (object interaction).

13. What is the Singleton pattern, and when is it used?

    • Type: Conceptual

    • Expected Answer: Singleton ensures a class has one instance and provides global access, used for logging or database connections.

    • Example:

      class Singleton {
        static instance = null;
        static getInstance() {
          if (!Singleton.instance) Singleton.instance = new Singleton();
          return Singleton.instance;
        }
      }

14. What is the Factory pattern?

    • Type: Conceptual

    • Expected Answer: Factory pattern creates objects without specifying the exact class, promoting flexibility.

    • Example:

      class CarFactory {
        createCar(type) {
          if (type === 'sedan') return new Sedan();
          return new SUV();
        }
      }

15. What is the Observer pattern?

    • Type: Conceptual

    • Expected Answer: Observer pattern allows objects to subscribe to and receive updates from a subject, used in event-driven systems.

    • Example: A newsletter system notifying subscribers of new content.

16. What is the difference between Adapter and Facade patterns?

    • Type: Conceptual

    • Expected Answer: Adapter converts one interface to another, while Facade simplifies a complex subsystem’s interface.

17. What is the Strategy pattern?

    • Type: Conceptual

    • Expected Answer: Strategy defines a family of algorithms, encapsulating them to be interchangeable, used for dynamic behavior selection.

    • Example:

      class PaymentStrategy {
        pay(amount) {}
      }
      class CreditCard extends PaymentStrategy {
        pay(amount) { return `Paid ${amount} via Credit Card`; }
      }

18. What is the Decorator pattern?

    • Type: Conceptual

    • Expected Answer: Decorator adds responsibilities to objects dynamically without modifying their code.

    • Example: Adding toppings to a pizza order.

19. Why are design patterns important in software development?

    • Type: Basic Understanding

    • Expected Answer: Design patterns promote code reuse, maintainability, and scalability by providing tested solutions.

20. What is the Builder pattern?

    • Type: Conceptual

    • Expected Answer: Builder separates complex object construction from its representation, allowing step-by-step creation.

    • Example:

      class HouseBuilder {
        constructor() { this.house = {}; }
        setWalls(walls) { this.house.walls = walls; return this; }
        build() { return this.house; }
      }

SDLC (Beginner)

21. What is the Software Development Life Cycle (SDLC)?

    • Type: Basic Understanding

    • Expected Answer: SDLC is a structured process for developing software, including phases like planning, design, development, testing, and maintenance.

    • Example: Waterfall model with sequential phases.

22. What are the main phases of SDLC?

    • Type: Conceptual

    • Expected Answer: Phases include Requirements Gathering, Design, Implementation, Testing, Deployment, and Maintenance.

23. Why is SDLC important in software development?

    • Type: Basic Understanding

    • Expected Answer: SDLC ensures systematic development, quality assurance, and timely delivery of software.

24. What is the Waterfall model in SDLC?

    • Type: Conceptual

    • Expected Answer: Waterfall is a linear SDLC model where each phase (e.g., requirements, design) completes before the next begins.

25. What are the advantages of the Waterfall model?

    • Type: Conceptual

    • Expected Answer: Simple, easy to manage, and suitable for projects with clear requirements.

26. What is the Agile model in SDLC?

    • Type: Conceptual

    • Expected Answer: Agile is an iterative SDLC model focusing on flexibility, collaboration, and incremental delivery.

27. What is the purpose of requirements gathering in SDLC?

    • Type: Practical

    • Expected Answer: It collects and documents user needs to define project scope and functionality.

28. What is the role of testing in SDLC?

    • Type: Conceptual

    • Expected Answer: Testing verifies that the software meets requirements and is free of defects.

29. What is a feasibility study in SDLC?

    • Type: Conceptual

    • Expected Answer: A feasibility study assesses a project’s technical, economic, and operational viability.

30. What is the difference between SRS and BRS?

    • Type: Conceptual

    • Expected Answer: SRS (Software Requirement Specification) is a detailed technical document, while BRS (Business Requirement Specification) outlines business needs.

Software Development (Beginner)

31. What is software development, and what does it involve?

    • Type: Basic Understanding

    • Expected Answer: Software development involves designing, coding, testing, and maintaining applications to solve problems or meet user needs.

32. What is the difference between frontend and backend development?

    • Type: Conceptual

    • Expected Answer: Frontend handles user interfaces, while backend manages server-side logic, databases, and APIs.

33. What is version control, and why is it used?

    • Type: Basic Understanding

    • Expected Answer: Version control (e.g., Git) tracks code changes, enabling collaboration and rollback.

    • Example:

      git commit -m "Add user login feature"

34. What is an API, and how is it used in software development?

    • Type: Conceptual

    • Expected Answer: An API (Application Programming Interface) enables communication between software components.

    • Example: Fetching data via a REST API.

      fetch('https://api.example.com/users')
        .then((res) => res.json())
        .then((data) => console.log(data));

35. What is debugging in software development?

    • Type: Practical

    • Expected Answer: Debugging identifies and fixes code errors using tools like breakpoints or logs.

36. What is the difference between a bug and a defect?

    • Type: Conceptual

    • Expected Answer: A bug is a coding error found during development, while a defect is an issue found in production.

37. What is unit testing, and why is it important?

    • Type: Conceptual

    • Expected Answer: Unit testing tests individual components to ensure they work correctly, improving code reliability.

38. What is the role of a code review in software development?

    • Type: Practical

    • Expected Answer: Code reviews ensure code quality, catch errors, and promote best practices.

39. What is continuous integration (CI)?

    • Type: Conceptual

    • Expected Answer: CI automates code integration and testing to catch issues early.

    • Example: Using Jenkins to run tests on code commits.

40. What is the difference between procedural and object-oriented programming?

    • Type: Conceptual

    • Expected Answer: Procedural programming focuses on procedures, while OOP organizes code into objects with properties and methods.

---

Intermediate-Level Questions

These questions target developers with 2–5 years of experience, focusing on real-world scenarios, practical applications, and deeper concepts.

Software Architecture (Intermediate)

41. How do you choose between monolithic and microservices architecture?

    • Type: Scenario-Based

    • Expected Answer: Choose monolithic for simplicity and small teams, microservices for scalability and independent deployments.

    • Scenario: When would you recommend microservices for an e-commerce platform?

42. What is event-driven architecture, and when is it used?

    • Type: Conceptual

    • Expected Answer: Event-driven architecture processes events asynchronously, ideal for real-time systems like notifications.

    • Example: A message queue handling order updates.

43. How do you ensure scalability in a distributed system?

    • Type: Practical

    • Expected Answer: Use load balancing, caching, and horizontal scaling.

    • Example: Implementing a load balancer with Nginx.

44. What is the role of middleware in software architecture?

    • Type: Conceptual

    • Expected Answer: Middleware facilitates communication between components, handling tasks like authentication or logging.

45. How do you design a RESTful API?

    • Type: Practical

    • Expected Answer: Use HTTP methods, stateless design, and clear endpoints.

    • Example:

      app.get('/users/:id', (req, res) => res.json(users[req.params.id]));

46. What is the difference between SOA and microservices?

    • Type: Conceptual

    • Expected Answer: SOA focuses on shared services, while microservices emphasize independent, fine-grained services.

47. How do you handle fault tolerance in a system?

    • Type: Scenario-Based

    • Expected Answer: Use redundancy, retries, and circuit breakers.

    • Example: Implementing a circuit breaker with a library like Hystrix.

48. What is the CAP theorem, and how does it affect architecture?

    • Type: Conceptual

    • Expected Answer: CAP theorem states a system can only guarantee two of Consistency, Availability, and Partition Tolerance, influencing database design.

49. How do you ensure security in software architecture?

    • Type: Practical

    • Expected Answer: Use encryption, authentication, and secure APIs.

    • Example: Implementing JWT for API authentication.

50. What is the role of caching in architecture?

    • Type: Practical

    • Expected Answer: Caching stores frequently accessed data to improve performance.

    • Example: Using Redis to cache API responses.

Design Patterns (Intermediate)

51. How do you implement the Factory Method pattern?

    • Type: Coding Challenge

    • Expected Answer:

      class VehicleFactory {
        createVehicle(type) {
          if (type === 'car') return new Car();
          return new Truck();
        }
      }

52. What is the Command pattern, and when is it used?

    • Type: Conceptual

    • Expected Answer: Command encapsulates a request as an object, used for undo operations or task queues.

    • Example: Implementing an undo feature in a text editor.

53. How do you use the Adapter pattern in a real-world scenario?

    • Type: Scenario-Based

    • Expected Answer: Adapter integrates incompatible interfaces, like adapting a legacy API to a new system.

    • Example:

      class LegacyAPI {
        oldRequest() { return 'Legacy Data'; }
      }
      class Adapter {
        constructor(legacy) { this.legacy = legacy; }
        request() { return this.legacy.oldRequest(); }
      }

54. What is the Composite pattern?

    • Type: Conceptual

    • Expected Answer: Composite treats individual and composite objects uniformly, used in tree-like structures.

    • Example: A file system with files and directories.

55. How do you implement the Observer pattern in JavaScript?

    • Type: Coding Challenge

    • Expected Answer:

      class Subject {
        observers = [];
        addObserver(observer) { this.observers.push(observer); }
        notify(data) { this.observers.forEach((obs) => obs.update(data)); }
      }

56. What is the difference between Strategy and State patterns?

    • Type: Conceptual

    • Expected Answer: Strategy swaps algorithms, while State changes behavior based on internal state.

57. How do you use the Decorator pattern in a real-world app?

    • Type: Scenario-Based

    • Expected Answer: Decorator adds functionality dynamically, like logging or validation in a service.

    • Example:

      class Coffee {
        cost() { return 5; }
      }
      class MilkDecorator {
        constructor(coffee) { this.coffee = coffee; }
        cost() { return this.coffee.cost() + 2; }
      }

58. What is the Template Method pattern?

    • Type: Conceptual

    • Expected Answer: Template Method defines a skeleton for an algorithm, allowing subclasses to override steps.

59. How do you implement the Singleton pattern in a thread-safe way?

    • Type: Coding Challenge

    • Expected Answer:

      class Singleton {
        static instance = null;
        static getInstance() {
          if (!Singleton.instance) {
            Singleton.instance = new Singleton();
          }
          return Singleton.instance;
        }
      }

60. What is the Chain of Responsibility pattern?

    • Type: Conceptual

    • Expected Answer: It passes requests along a chain of handlers, used in middleware or event processing.

SDLC (Intermediate)

61. What is the difference between Waterfall and Agile models?

    • Type: Conceptual

    • Expected Answer: Waterfall is linear and rigid, while Agile is iterative and flexible.

62. How does risk management fit into SDLC?

    • Type: Scenario-Based

    • Expected Answer: Risk management identifies and mitigates risks during each SDLC phase, like scope creep or delays.

63. What is the role of verification vs. validation in SDLC?

    • Type: Conceptual

    • Expected Answer: Verification ensures the product is built correctly, while validation ensures it meets user needs.

64. How do you handle changing requirements in Agile?

    • Type: Scenario-Based

    • Expected Answer: Use iterative sprints, backlog grooming, and stakeholder feedback to adapt to changes.

65. What is the Spiral model in SDLC?

    • Type: Conceptual

    • Expected Answer: Spiral combines iterative development with risk analysis, suitable for complex projects.

66. How do you ensure quality in the testing phase of SDLC?

    • Type: Practical

    • Expected Answer: Use automated testing, manual testing, and test-driven development (TDD).

67. What is the role of documentation in SDLC?

    • Type: Conceptual

    • Expected Answer: Documentation ensures clarity, traceability, and maintainability across SDLC phases.

68. How do you prioritize requirements in SDLC?

    • Type: Scenario-Based

    • Expected Answer: Use techniques like MoSCoW prioritization or stakeholder input to rank requirements.

69. What is the DevOps model in SDLC?

    • Type: Conceptual

    • Expected Answer: DevOps integrates development and operations for continuous delivery and automation.

70. How do you manage scope creep in SDLC?

    • Type: Scenario-Based

    • Expected Answer: Use change control processes, stakeholder alignment, and clear requirements.

Software Development (Intermediate)

71. How do you implement CI/CD pipelines?

    • Type: Practical

    • Expected Answer: Use tools like Jenkins or GitHub Actions to automate builds, tests, and deployments.

    • Example:

      name: CI
      on: [push]
      jobs:
        build:
          runs-on: ubuntu-latest
          steps:
            - uses: actions/checkout@v3
            - run: npm test

72. What is test-driven development (TDD)?

    • Type: Conceptual

    • Expected Answer: TDD involves writing tests before code to ensure functionality and reduce bugs.

73. How do you handle performance bottlenecks in an application?

    • Type: Scenario-Based

    • Expected Answer: Profile the app, optimize queries, and use caching.

    • Example: Optimizing a slow database query with indexing.

74. What is the role of refactoring in software development?

    • Type: Practical

    • Expected Answer: Refactoring improves code structure without changing functionality, enhancing maintainability.

75. How do you implement authentication in a web app?

    • Type: Coding Challenge

    • Expected Answer:

      const jwt = require('jsonwebtoken');
      function authenticate(req, res, next) {
        const token = req.headers['authorization'];
        if (!token) return res.status(401).send('Unauthorized');
        jwt.verify(token, 'secret', (err, user) => {
          if (err) return res.status(403).send('Invalid token');
          req.user = user;
          next();
        });
      }

76. What is the difference between integration and unit testing?

    • Type: Conceptual

    • Expected Answer: Unit testing tests individual components, while integration testing tests their interactions.

77. How do you handle cross-browser compatibility?

    • Type: Practical

    • Expected Answer: Use polyfills, CSS resets, and testing tools like BrowserStack.

78. What is the role of a package manager in software development?

    • Type: Conceptual

    • Expected Answer: Package managers (e.g., npm) manage dependencies and streamline development.

79. How do you optimize a frontend application?

    • Type: Practical

    • Expected Answer: Minify assets, use lazy loading, and optimize rendering.

    • Example: Lazy loading images with loading="lazy".

80. What is the difference between synchronous and asynchronous programming?

    • Type: Conceptual

    • Expected Answer: Synchronous code executes sequentially, while asynchronous code allows non-blocking operations.

    • Example:

      async function fetchData() {
        const res = await fetch('https://api.example.com');
        return res.json();
      }

---

Expert-Level Questions

These questions challenge senior developers with complex scenarios, advanced patterns, and critical system design tasks.

Software Architecture (Expert)

81. How do you design a scalable microservices architecture?

    • Type: Scenario-Based

    • Expected Answer: Use domain-driven design, API gateways, and message queues.

    • Example: Implementing Kafka for inter-service communication.

82. What is domain-driven design (DDD)?

    • Type: Conceptual

    • Expected Answer: DDD aligns software design with business domains, using bounded contexts and aggregates.

83. How do you handle eventual consistency in distributed systems?

    • Type: Scenario-Based

    • Expected Answer: Use event sourcing, sagas, or compensating transactions.

84. What is the role of an API gateway in microservices?

    • Type: Conceptual

    • Expected Answer: An API gateway routes requests, handles authentication, and aggregates responses.

85. How do you design a system for high availability?

    • Type: Scenario-Based

    • Expected Answer: Use redundancy, failover mechanisms, and load balancing.

    • Example: Deploying a system across multiple AWS regions.

86. What is the difference between CQRS and traditional CRUD?

    • Type: Conceptual

    • Expected Answer: CQRS separates command (write) and query (read) operations for scalability and flexibility.

87. How do you implement circuit breakers in a distributed system?

    • Type: Coding Challenge

    • Expected Answer:

      class CircuitBreaker {
        constructor(threshold) { this.failures = 0; this.threshold = threshold; }
        async execute(fn) {
          if (this.failures >= this.threshold) throw new Error('Circuit open');
          try {
            return await fn();
          } catch (err) {
            this.failures++;
            throw err;
          }
        }
      }

88. What is the role of message queues in architecture?

    • Type: Conceptual

    • Expected Answer: Message queues decouple services, enabling asynchronous communication and scalability.

    • Example: Using RabbitMQ for task queues.

89. How do you ensure data consistency in microservices?

    • Type: Scenario-Based

    • Expected Answer: Use distributed transactions, event sourcing, or saga patterns.

90. What is the difference between vertical and horizontal scaling?

    • Type: Conceptual

    • Expected Answer: Vertical scaling adds resources to a single machine, while horizontal scaling adds more machines.

Design Patterns (Expert)

91. How do you implement the Saga pattern in a microservices architecture?

    • Type: Coding Challenge

    • Expected Answer:

      class Saga {
        async execute(steps) {
          for (const step of steps) {
            try {
              await step.execute();
            } catch (err) {
              await step.compensate();
              throw err;
            }
          }
        }
      }

92. What is the Mediator pattern, and when is it used?

    • Type: Conceptual

    • Expected Answer: Mediator centralizes communication between objects, reducing coupling in complex systems.

93. How do you implement the Visitor pattern?

    • Type: Coding Challenge

    • Expected Answer:

      class Visitor {
        visitElement(element) { element.accept(this); }
      }
      class Element {
        accept(visitor) { visitor.visit(this); }
      }

94. What is the difference between Proxy and Decorator patterns?

    • Type: Conceptual

    • Expected Answer: Proxy controls access to an object, while Decorator adds functionality.

95. How do you use the Flyweight pattern to optimize memory?

    • Type: Scenario-Based

    • Expected Answer: Flyweight shares common data across objects to reduce memory usage.

    • Example: Storing shared character data in a text editor.

96. What is the Memento pattern, and when is it used?

    • Type: Conceptual

    • Expected Answer: Memento captures and restores an object’s state, used for undo functionality.

97. How do you implement the Command pattern for undo operations?

    • Type: Coding Challenge

    • Expected Answer:

      class Command {
        execute() {}
        undo() {}
      }
      class EditorCommand extends Command {
        constructor(text, editor) { this.text = text; this.editor = editor; }
        execute() { this.editor.add(this.text); }
        undo() { this.editor.remove(this.text); }
      }

98. What is the Bridge pattern?

    • Type: Conceptual

    • Expected Answer: Bridge decouples abstraction from implementation, allowing independent variation.

99. How do you use the Composite pattern in a UI framework?

    • Type: Scenario-Based

    • Expected Answer: Composite treats UI components (e.g., buttons, panels) uniformly in a tree structure.

100. What is the difference between Facade and Mediator patterns?

     • Type: Conceptual

     • Expected Answer: Facade simplifies a subsystem’s interface, while Mediator manages object interactions.

SDLC (Expert)

101. How do you integrate DevOps into SDLC?

     • Type: Scenario-Based

     • Expected Answer: Use CI/CD pipelines, infrastructure as code, and monitoring tools for continuous delivery.

102. What is the role of Kanban in Agile SDLC?

     • Type: Conceptual

     • Expected Answer: Kanban visualizes workflows, limits work in progress, and optimizes flow in Agile projects.

103. How do you handle technical debt in SDLC?

     • Type: Scenario-Based

     • Expected Answer: Prioritize refactoring, allocate time for debt reduction, and track debt in the backlog.

104. What is the role of prototyping in SDLC?

     • Type: Conceptual

     • Expected Answer: Prototyping validates requirements and designs early, reducing risks.

105. How do you ensure traceability in SDLC?

     • Type: Practical

     • Expected Answer: Use tools like JIRA to link requirements, code, and tests.

106. What is the V-Model in SDLC?

     • Type: Conceptual

     • Expected Answer: V-Model pairs each development phase with a testing phase for validation.

107. How do you manage stakeholder conflicts in SDLC?

     • Type: Scenario-Based

     • Expected Answer: Facilitate communication, prioritize requirements, and align on project goals.

108. What is the role of metrics in SDLC?

     • Type: Practical

     • Expected Answer: Metrics like velocity or defect rates measure progress and quality.

109. How do you scale Agile for large teams?

     • Type: Scenario-Based

     • Expected Answer: Use frameworks like SAFe or Scrum of Scrums for coordination.

110. What is the difference between iterative and incremental development?

     • Type: Conceptual

     • Expected Answer: Iterative refines the product through cycles, while incremental builds it in parts.

Software Development (Expert)

111. How do you optimize database queries in a large-scale application?

     • Type: Scenario-Based

     • Expected Answer: Use indexing, query optimization, and caching.

     • Example:

       CREATE INDEX idx_user_id ON users(id);

112. What is the role of design reviews in software development?

     • Type: Conceptual

     • Expected Answer: Design reviews validate architecture and design decisions, ensuring alignment with requirements.

113. How do you implement a microfrontend architecture?

     • Type: Scenario-Based

     • Expected Answer: Use module federation or iframes to integrate independent frontend apps.

     • Example: Webpack Module Federation configuration.

114. What is the difference between TDD and BDD?

     • Type: Conceptual

     • Expected Answer: TDD focuses on unit tests, while BDD emphasizes behavior-driven specifications.

115. How do you handle legacy code in a project?

     • Type: Scenario-Based

     • Expected Answer: Refactor incrementally, write tests, and document changes.

116. What is the role of containerization in software development?

     • Type: Practical

     • Expected Answer: Containerization (e.g., Docker) ensures consistent environments.

     • Example:

       FROM node:16
       COPY . /app
       CMD ["npm", "start"]

117. How do you implement real-time features in an app?

     • Type: Coding Challenge

     • Expected Answer:

       const socket = new WebSocket('ws://example.com');
       socket.onmessage = (event) => console.log(event.data);

118. What is the role of observability in software development?

     • Type: Conceptual

     • Expected Answer: Observability uses logs, metrics, and traces to monitor system health.

119. How do you secure a REST API?

     • Type: Practical

     • Expected Answer: Use HTTPS, JWT, and rate limiting.

     • Example:

       app.use(require('express-rate-limit')({ max: 100, windowMs: 15 * 60 * 1000 }));

120. What is the difference between blue-green and canary deployments?

     • Type: Conceptual

     • Expected Answer: Blue-green deploys two environments, while canary releases to a subset of users.

121. How do you implement a search feature with pagination?

     • Type: Coding Challenge

     • Expected Answer:

       app.get('/search', async (req, res) => {
         const { query, page = 1 } = req.query;
         const results = await db.search(query).skip((page - 1) * 10).limit(10);
         res.json(results);
       });

122. What is the role of A/B testing in software development?

     • Type: Conceptual

     • Expected Answer: A/B testing compares two versions to determine which performs better.

123. How do you handle distributed transactions?

     • Type: Scenario-Based

     • Expected Answer: Use two-phase commit or saga patterns for consistency.

124. What is the difference between SOA and microservices in practice?

     • Type: Conceptual

     • Expected Answer: SOA uses shared services, while microservices are independently deployable.

125. How do you implement rate limiting in an API?

     • Type: Coding Challenge

     • Expected Answer:

       const rateLimit = require('express-rate-limit');
       app.use(rateLimit({ windowMs: 15 * 60 * 1000, max: 100 }));

126. What is the role of static analysis in software development?

     • Type: Conceptual

     • Expected Answer: Static analysis checks code for errors without execution, improving quality.

127. How do you optimize frontend-backend communication?

     • Type: Scenario-Based

     • Expected Answer: Use efficient APIs, caching, and batch requests.

128. What is the difference between REST and GraphQL?

     • Type: Conceptual

     • Expected Answer: REST uses fixed endpoints, while GraphQL allows flexible queries.

129. How do you implement a caching strategy for a web app?

     • Type: Practical

     • Expected Answer: Use in-memory caches like Redis or browser caching.

     • Example:

       const redis = require('redis');
       const client = redis.createClient();
       client.setex('key', 3600, 'value');

130. What is the role of dependency injection in software development?

     • Type: Conceptual

     • Expected Answer: Dependency injection decouples components by passing dependencies externally.

131. How do you implement a feature toggle system?

     • Type: Coding Challenge

     • Expected Answer:

       class FeatureToggle {
         constructor(toggles) { this.toggles = toggles; }
         isEnabled(feature) { return this.toggles[feature] || false; }
       }

132. What is the role of chaos engineering in software development?

     • Type: Conceptual

     • Expected Answer: Chaos engineering tests system resilience by introducing failures.

133. How do you handle database migrations?

     • Type: Practical

     • Expected Answer: Use tools like Flyway or Liquibase for automated migrations.

     • Example:

       ALTER TABLE users ADD COLUMN email VARCHAR(255);

134. What is the difference between monolithic and serverless architectures?

     • Type: Conceptual

     • Expected Answer: Monolithic is a single app, while serverless uses managed functions for scalability.

135. How do you implement a logging system?

     • Type: Coding Challenge

     • Expected Answer:

       const winston = require('winston');
       const logger = winston.createLogger({
         transports: [new winston.transports.File({ filename: 'app.log' })],
       });

136. What is the role of code coverage in testing?

     • Type: Conceptual

     • Expected Answer: Code coverage measures the percentage of code tested, ensuring thorough testing.

137. How do you handle internationalization in a web app?

     • Type: Practical

     • Expected Answer: Use libraries like i18next for translations.

     • Example:

       import i18n from 'i18next';
       i18n.init({ resources: { en: { translation: { welcome: 'Welcome' } } } });

138. What is the difference between load testing and stress testing?

     • Type: Conceptual

     • Expected Answer: Load testing checks performance under expected load, while stress testing tests system limits.

139. How do you implement a retry mechanism for API calls?

     • Type: Coding Challenge

     • Expected Answer:

       async function fetchWithRetry(url, retries = 3) {
         for (let i = 0; i < retries; i++) {
           try {
             const res = await fetch(url);
             return await res.json();
           } catch (err) {
             if (i === retries - 1) throw err;
           }
         }
       }

140. What is the role of domain events in DDD?

     • Type: Conceptual

     • Expected Answer: Domain events capture significant state changes in a domain, enabling decoupled communication.

141. How do you implement a circuit breaker pattern in a microservice?

     • Type: Coding Challenge

     • Expected Answer:

       class CircuitBreaker {
         constructor(threshold) { this.failures = 0; this.threshold = threshold; }
         async execute(fn) {
           if (this.failures >= this.threshold) throw new Error('Circuit open');
           try {
             return await fn();
           } catch (err) {
             this.failures++;
             throw err;
           }
         }
       }

142. What is the difference between orchestration and choreography in microservices?

     • Type: Conceptual

     • Expected Answer: Orchestration centralizes control, while choreography distributes coordination among services.

143. How do you implement a background job system?

     • Type: Practical

     • Expected Answer: Use tools like Bull or Sidekiq for job queues.

     • Example:

       const Queue = require('bull');
       const jobQueue = new Queue('jobs');
       jobQueue.process((job) => processJob(job.data));

144. What is the role of API versioning?

     • Type: Conceptual

     • Expected Answer: API versioning ensures backward compatibility as APIs evolve.

145. How do you handle cross-cutting concerns in a system?

     • Type: Scenario-Based

     • Expected Answer: Use aspects, middleware, or decorators for concerns like logging or authentication.

146. What is the difference between event sourcing and traditional databases?

     • Type: Conceptual

     • Expected Answer: Event sourcing stores state changes as events, while traditional databases store current state.

147. How do you implement a rate limiter for a distributed system?

     • Type: Coding Challenge

     • Expected Answer:

       const Redis = require('redis');
       async function rateLimit(key, limit, window) {
         const client = Redis.createClient();
         const count = await client.get(key) || 0;
         if (count >= limit) return false;
         await client.setex(key, window, count + 1);
         return true;
       }

148. What is the role of service discovery in microservices?

     • Type: Conceptual

     • Expected Answer: Service discovery enables services to find and communicate with each other dynamically.

149. How do you implement a health check endpoint?

     • Type: Coding Challenge

     • Expected Answer:

       app.get('/health', (req, res) => {
         const status = db.isConnected() ? 'healthy' : 'unhealthy';
         res.json({ status });
       });

150. What is the difference between synchronous and asynchronous messaging?

     • Type: Conceptual

     • Expected Answer: Synchronous messaging waits for a response, while asynchronous messaging does not.

151. How do you implement a distributed cache?

     • Type: Practical

     • Expected Answer: Use Redis or Memcached for distributed caching.

     • Example:

       const redis = require('redis');
       const client = redis.createClient();
       client.setex('cacheKey', 3600, JSON.stringify(data));

152. What is the role of polyglot persistence in architecture?

     • Type: Conceptual

     • Expected Answer: Polyglot persistence uses multiple database types to optimize data storage.

153. How do you handle schema evolution in a database?

     • Type: Scenario-Based

     • Expected Answer: Use backward-compatible changes and migration scripts.

154. What is the role of a service mesh in microservices?

     • Type: Conceptual

     • Expected Answer: A service mesh manages service-to-service communication, providing observability and security.

155. How do you implement a distributed tracing system?

     • Type: Practical

     • Expected Answer: Use tools like Jaeger or Zipkin to trace requests across services.

     • Example:

       const tracer = require('jaeger-client').initTracer(config);
       const span = tracer.startSpan('request');
       span.finish();

📘Free Job Preparation Zone 🎯 Visit Free Learning Zone