This is a solid approach—testing a senior C# engineer’s hands-on experience through real-world scenarios. Below is a comprehensive list of
at least 30 in-depth senior-level interview questions with detailed explanations and answers. These questions focus on transaction handling, distributed systems, performance optimization, security, and system design—all crucial in a financial organization and industry as a whole.
1) TRANSACTION FAILURE AND RETRY MECHANISMS
ANSWER
The best approach is to use a retry mechanism with idempotency. This can be done via:
- Implementing a retry policy using Polly:
Retries up to 3 times before failing.
Uses exponential backoff to prevent overload.
- Using a background job queue (Hangfire, Quartz.NET, or MassTransit):
- Database-based tracking:
2. Deadlocks in SQL Transactions
ANSWER
- Use a consistent ordering of operations:
- Always debit before credit to prevent deadlocks.
- Lower the lock scope:
- Retry logic in case of deadlock:
3. Handling High-Volume Concurrent Transactions
Answer:
4. Preventing Double-Spending in Distributed Transactions
Answer:
5. Optimizing Database Queries for Real-Time Processing
Answer:
- Use database indexing:
- Use pagination for large queries:
6. Securing API Requests & Authentication
Answer:
7. Handling Long-Running Processes in .NET
Answer:
8. Handling Race Conditions in Multi-Threaded Environments
Answer
- Use database transactions with row-level locks:
9. Logging & Monitoring in Production
Answer:
10. Handling API Failures in a Microservices Architecture
Answer:
11. Handling Concurrency in a Banking System
Answer:
12. Preventing API Rate Abuse
Answer:
13. Ensuring Data Consistency Across Microservices
Answer:
14. Secure Storage of Sensitive User Data
Answer
15. Designing a Real-Time Fraud Detection System
Answer:
16. Avoiding Memory Leaks in Long-Running Services
Answer:
17. Designing a Scalable Logging System
Answer
18. Handling Time Zones in a Global Financial System
Answer
19. Scaling a .NET API to Handle Millions of Requests
Answer:
20. Optimizing SQL Queries for Large Data Processing
Answer:
21. Handling Large Reports in a Financial System
Answer
22. Eventual Consistency in Distributed Systems
Answer
23. Implementing Circuit Breakers in Microservices
Answer
24. Preventing Unauthorized Transactions
Answer:
25. Caching Strategies for Real-Time Banking Data
Answer:
26. Secure Storage of API Keys
Answer
27. WebSockets vs SignalR for Real-Time Updates
Answer
28. Handling Mass Fund Transfers Efficiently
Answer:
29. Role-Based Access Control (RBAC) in a Banking App
Answer:
30. Building an Event-Driven Architecture for Bank Notifications
Answer:
31. Using CQRS with Separate Read and Write Models in a Financial App
Answer:
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Credit: Graphics sourced from CodeQuotient
Top comments (8)
Thanks for sharing !!! Some answers were blank. Will be nice to add some implementation as well .
Thank you for your feedback! The answers should now be fully displayed. I’ll update it with some implementations soon as well.
Should be titled senior database engineer with the amount of db related questions!
Haha, you’re right! Seems like the database questions definitely took the spotlight.
Mastering the interview for a Senior C# Engineer is not a walk in the park, but with proper preparation, it's definitely doable! Focusing on advanced concepts in C#, system design, and problem-solving really gives one the edge. Good luck to all those preparing; just be confident and keep practicing!
Please prefer text to images for the answers. It's more accessible.
Or add alt messages.
Thanks for sharing. It's helpful.
The images were also very impractical to read on a mobile phone. I had to zoom and scroll each image to read. It quickly became frustrating.
I did love the content though. Lots of pearls of wisdom.