Q1
Design a RESTful API endpoint for a user authentication system. Walk us through your approach to handling token refresh, session management, and security considerations like rate limiting and password hashing.
Why they ask this:* They want to assess your understanding of API design principles, security best practices, and real-world authentication challenges that mid-level developers frequently encounter.
Q2
Explain the differences between SQL and NoSQL databases. When would you choose one over the other, and can you describe a scenario where you've made this decision in a production system?
Why they ask this:* This evaluates your database architecture knowledge and ability to make trade-off decisions based on application requirements, a critical skill for mid-level backend developers.
Q3
How would you optimize a database query that's taking 5 seconds to return results on a table with 10 million rows? Walk through your debugging and optimization process.
Why they ask this:* They're testing your practical problem-solving skills, knowledge of indexing, query optimization techniques, and whether you can diagnose performance issues systematically.
Q4
Describe your experience with message queues or event-driven architectures (e.g., RabbitMQ, Kafka, AWS SQS). How have you used them to solve a specific backend problem?