Acronis India Backend Engineer Interview: Rounds, Questions and Preparation

What the job involves

Backend engineers at global tech companies design, build, and maintain server-side logic, APIs, and databases that power applications used by millions. They work with cloud infrastructure, write scalable code, and collaborate with frontend and DevOps teams to ensure reliability and performance. Day to day involves coding, debugging, code reviews, and optimizing systems for speed and cost.

Role and Technical Knowledge

1. 1

   Explain the difference between SQL and NoSQL databases. When would you choose one over the other for a backend service?

   Cover structured vs unstructured data, scalability, and use cases like transactions vs flexible schemas. Mention examples such as PostgreSQL and MongoDB.

2. 2

   What is a RESTful API? How would you design an endpoint for retrieving a user's profile?

   Describe REST principles, HTTP methods, status codes, and a clear URL structure like GET /users/{id}. Mention authentication and versioning.

3. 3

   How does a load balancer work in a backend architecture? Why is it important?

   Explain distribution of incoming traffic across servers, health checks, and benefits like high availability and scalability. Mention algorithms like round-robin.

4. 4

   What are the key differences between processes and threads? How does this affect backend performance?

   Discuss memory sharing, context switching, and concurrency. Relate to handling multiple requests efficiently in a server application.

Practical Scenarios

1. 5

   You notice an API endpoint is responding slowly. How would you diagnose and fix the issue?

   Outline steps: check logs, monitor resource usage, profile database queries, and consider caching or indexing. Emphasize systematic debugging.

2. 6

   How would you design a simple URL shortener service like bit.ly?

   Cover requirements, database schema, hashing or encoding for short keys, and handling redirects. Mention scalability and collision avoidance.

3. 7

   You need to store user session data for a web application. What approach would you take and why?

   Compare options like in-memory stores (Redis), databases, or cookies. Discuss trade-offs in speed, persistence, and scalability.

4. 8

   Describe a time you had to debug a tricky issue in a project. What was your process?

   Use STAR method: situation, task, action, result. Highlight logical steps, tools used, and what you learned.

Behavioural and HR

1. 9

   Why do you want to work as a backend engineer at a global tech company?

   Show passion for backend systems, scalability, and impact. Mention specific interests like cloud or distributed systems, and alignment with company values.

2. 10

   Tell me about a time you worked in a team to complete a project. What was your role?

   Demonstrate collaboration, communication, and contribution. Use a concrete example from college or internship.

3. 11

   How do you handle tight deadlines or conflicting priorities?

   Show time management, prioritization, and calm under pressure. Give an example of how you delivered despite challenges.

4. 12

   Where do you see yourself in five years?

   Express growth in technical skills, possibly leading projects or mentoring. Align with long-term career in backend development.

Advanced Concepts and Best Practices

1. 13

   What is database indexing? How does it improve query performance, and what are the trade-offs?

   Explain how indexes speed up reads but slow writes and use extra space. Mention types like B-tree and when to use them.

2. 14

   Explain the concept of microservices. What are the advantages and challenges compared to a monolithic architecture?

   Cover independence, scalability, and technology diversity vs complexity in deployment, debugging, and data consistency.

3. 15

   How would you ensure the security of a backend API?

   Discuss authentication (OAuth, JWT), authorization, input validation, HTTPS, rate limiting, and protection against common attacks like SQL injection.

4. 16

   What is caching? Where would you implement it in a backend system?

   Describe caching layers (client, CDN, server, database) and strategies like TTL, LRU. Mention tools like Redis and benefits like reduced latency.