back end web developer Interview Questions and Answers

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100 Back End Web Developer Interview Questions and Answers

  1. What is RESTful API and how does it work?

    • Answer: A RESTful API (Representational State Transfer Application Programming Interface) is an architectural style for building web services. It uses HTTP methods (GET, POST, PUT, DELETE) to perform operations on resources. Each resource is identified by a unique URI. The client sends requests to the server, and the server responds with data in a format like JSON or XML. It relies on statelessness (each request contains all the information needed), client-server architecture, and a layered system for better scalability and maintainability.

  2. Explain the difference between GET and POST requests.

    • Answer: GET requests retrieve data from the server. They are idempotent (making the same request multiple times has the same effect) and are typically used for retrieving resources. POST requests send data to the server to create or update a resource. They are not idempotent and are often used for submitting forms or creating new entries in a database.

  3. What are some common HTTP status codes and their meanings?

    • Answer: 200 OK (successful request), 400 Bad Request (client-side error), 401 Unauthorized (authentication required), 404 Not Found (resource not found), 500 Internal Server Error (server-side error).

  4. What is SQL injection and how can it be prevented?

    • Answer: SQL injection is a code injection technique that exploits vulnerabilities in database interactions. Attackers inject malicious SQL code into input fields to manipulate database queries. Prevention involves parameterized queries (prepared statements), input validation, and escaping special characters.

  5. What is the difference between a database and a NoSQL database?

    • Answer: SQL databases use a structured schema with predefined tables and relationships, enforcing data integrity. NoSQL databases are more flexible, offering various data models (document, key-value, graph) and are better suited for unstructured or semi-structured data and high scalability.

  6. Explain the concept of normalization in databases.

    • Answer: Normalization is a process of organizing data to reduce redundancy and improve data integrity. Different normal forms (1NF, 2NF, 3NF, etc.) define levels of redundancy reduction. It involves splitting large tables into smaller ones and defining relationships between them.

  7. What is ORM (Object-Relational Mapping)?

    • Answer: ORM is a programming technique that maps objects in programming languages to rows in a relational database. It simplifies database interactions by allowing developers to work with objects instead of writing SQL queries directly.

  8. What is caching and why is it important?

    • Answer: Caching is storing frequently accessed data in a temporary storage location (cache) to speed up access. It reduces database load, improves application performance, and enhances user experience.

  9. What are some common caching strategies?

    • Answer: Common strategies include server-side caching (e.g., Redis, Memcached), client-side caching (e.g., browser caching), and CDN caching.

  10. Explain the concept of load balancing.

    • Answer: Load balancing distributes network or application traffic across multiple servers to prevent overload and ensure high availability. It improves performance, scalability, and fault tolerance.

  11. Describe your experience with version control systems like Git.

    • Answer: [Describe your specific experience with Git, including branching, merging, pull requests, resolving conflicts, and using platforms like GitHub or GitLab.]

  12. How do you handle errors and exceptions in your code?

    • Answer: [Describe your approach to error handling, including using try-catch blocks, logging errors, and implementing custom error handling mechanisms.]

  13. What design patterns are you familiar with and how have you used them?

    • Answer: [List familiar design patterns like Singleton, Factory, MVC, and describe how you've applied them in your projects.]

  14. Explain your understanding of microservices architecture.

    • Answer: [Describe microservices, their benefits (scalability, maintainability), and potential challenges (communication overhead, distributed tracing).]

  15. What experience do you have with message queues (e.g., RabbitMQ, Kafka)?

    • Answer: [Describe your experience with message queues, including use cases for asynchronous communication, decoupling services, and handling high volumes of messages.]

  16. What are your preferred testing methodologies for backend code?

    • Answer: [Discuss unit testing, integration testing, and end-to-end testing, explaining your approach to writing effective tests.]

  17. How do you ensure the security of your backend applications?

    • Answer: [Describe security practices, including input validation, authentication and authorization, encryption, and protection against common vulnerabilities like SQL injection and cross-site scripting (XSS).]

  18. What are your preferred programming languages and frameworks for backend development?

    • Answer: [List your preferred languages (e.g., Python, Java, Node.js) and frameworks (e.g., Django, Spring Boot, Express.js), explaining your reasons for choosing them.]

  19. Describe a challenging problem you faced in a backend project and how you solved it.

    • Answer: [Describe a specific challenge, outlining the problem, your approach to troubleshooting, and the solution you implemented.]

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