Backend Developer Interview Questions
In the evolving landscape of software development, backend developers remain the unsung heroes, orchestrating the seamless functionality behind every user interaction. As businesses strive to find the best talent to steward their data, integrate systems, and scale their digital infrastructure, effective interviewing becomes paramount. This article delves into 25 meticulously curated interview questions tailored for backend developers, ensuring you're well-equipped to assess expertise ranging from database management to modern security protocols. Whether you're hiring or preparing to be interviewed, these questions offer a comprehensive overview of what defines a proficient backend developer.
Explain the concept of REST.
Answer: REST stands for Representational State Transfer. It's an architectural style for designing networked applications using a stateless protocol, typically HTTP, and conventions based on CRUD operations.
What is a Microservice architecture?
Answer: Microservices is an architectural style that structures an application as a collection of small, loosely coupled, and independently deployable services.
How do you handle database migrations?
Answer: Tools like Flyway or Liquibase can be used, or ORM tools with migration support such as Django's ORM or SQLAlchemy for Python.
How would you prevent SQL injection?
Answer: By using parameterized queries or prepared statements, avoiding raw SQL queries wherever possible, and consistently validating and sanitizing user input.
What is the CAP theorem?
Answer: It states that it's impossible for a distributed data store to simultaneously provide Consistency, Availability, and Partition Tolerance. At most, it can achieve only two out of the three.
What is a Message Queue and name a few?
Answer: A message queue is a form of asynchronous service-to-service communication. Examples include RabbitMQ, Apache Kafka, and AWS SQS.
How do you manage sessions in a distributed environment?
Answer: Sessions can be managed using sticky sessions, centralized session stores, or token-based authentication like JWT.
How would you handle data integrity in a microservices architecture?
Answer: By implementing distributed transactions using patterns such as Two-Phase Commit or the Saga pattern.
What is ORM?
Answer: ORM stands for Object-Relational Mapping. It's a technique that lets you interact with your database using an object paradigm.
How do you handle logging in a multi-service environment?
Answer: Centralized logging solutions like ELK (Elasticsearch, Logstash, Kibana) stack or Splunk can be used.
Explain the difference between NoSQL and SQL databases.
Answer: SQL databases are relational, while NoSQL databases can be document-based, key-value pairs, wide-column stores, or graph databases.
What is lazy loading?
Answer: Lazy loading is a design pattern that delays initialization or population of an object until it's actually needed.
How do you handle exceptions in a backend application?
Answer: By using try-catch blocks, centralized exception handling mechanisms, and proper logging.
Describe the OAuth authentication process.
Answer: OAuth allows third-party services to exchange your information without revealing your password. It typically involves three parties: the user, the consumer, and the service provider.
How do you ensure data consistency across microservices?
Answer: By using event-driven architecture, implementing idempotency, and leveraging distributed transactions or compensation transactions.
What is caching? Name some caching mechanisms.
Answer: Caching is storing a copy of data in a location for faster access in subsequent requests. Examples include Redis, Memcached, and Varnish.
How do you maintain ACID properties in distributed databases?
Answer: Through distributed transactions, implementing patterns like Two-Phase Commit, and by using databases that support ACID across nodes.
How would you implement authentication and authorization?
Answer: Authentication can be implemented using JWT, OAuth, or basic auth mechanisms. Authorization can be handled using roles, claims, or ACLs.
What is a reverse proxy and why is it used?
Answer: A reverse proxy takes client requests and forwards them to servers. It's used for load balancing, security, and caching.
How do you handle file uploads in a web application?
Answer: By using multipart form requests, storing the file in a blob storage or file system, and maintaining metadata in databases.
What are web sockets?
Answer: WebSockets provide full-duplex communication channels over a single TCP connection, allowing for real-time communication.
How do you manage API versioning?
Answer: Through URI versioning, request header versioning, or accept header versioning.
What are rate limiting strategies?
Answer: Token bucket, leaky bucket, and fixed window counters are common strategies.
How do you ensure backend scalability?
Answer: By employing load balancing, optimizing databases, using caching mechanisms, and building stateless applications.
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