Senior .NET Developer Interview Questions

Introduction

Hiring the right Senior .NET Developer is critical in Information Technology (IT). The role demands deep technical knowledge, architectural judgement, and strong collaboration skills to deliver reliable, maintainable software.

This guide provides practical Senior .NET Developer interview questions for basic, intermediate, and advanced screening. It also includes pre-screening interview questions designed for one-way video interviews to help recruiters and hiring managers streamline selection.

Senior .NET Developer Interview Questions

Basic Senior .NET Developer Interview Questions

• Explain the differences between the .NET Framework, .NET Core, and .NET 5+.
• How does garbage collection work in .NET and what are generations?
• What are the core principles of object oriented programming and how do you apply them in C#?
• Describe async and await in C#. When would you use asynchronous programming?
• How does LINQ work and give a simple example of a LINQ query on a collection.
• What is dependency injection and why is it useful in .NET applications?
• Explain the difference between value types and reference types in C#.
• How do you handle exceptions in a .NET application and what are best practices?

Intermediate Senior .NET Developer Interview Questions

• You inherit a legacy Web API with performance issues. How would you diagnose and improve response time?
• Describe how you would design a RESTful API in ASP.NET Core for a resource-heavy domain.
• Give an example of using Entity Framework Core. How do you manage migrations and prevent N+1 queries?
• How do you implement and configure caching for a high-read .NET service?
• Explain a scenario where you would use background processing with IHostedService or a message queue.
• How do you approach secure authentication and authorization in an enterprise .NET app?
• Describe strategies for unit testing and integration testing .NET components, including mocks.
• How would you refactor a monolithic .NET app to improve maintainability without changing behavior?
• Explain how you use async streams or IAsyncEnumerable to process large data sets efficiently.
• Describe how you configure CI/CD pipelines for .NET builds, tests, and deployments.

Advanced Senior .NET Developer Interview Questions

• Design an architecture for a scalable microservices system using .NET components. What are key trade offs?
• How do you perform performance profiling in a production .NET application and act on findings?
• Explain strategies for data consistency across distributed .NET services, including sagas and event sourcing.
• Discuss advanced concurrency patterns in .NET and how you avoid deadlocks and race conditions.
• How do you design a resilient API layer to handle downstream failures and high load?
• Describe how you would optimize memory usage and reduce GC pressure in a high-throughput .NET service.
• How do you evaluate and adopt cloud-native services for a .NET application in Azure or other clouds?
• Explain how observability is implemented: logging, metrics, tracing for .NET applications at scale.
• Describe a technical design review you led and how you balanced technical debt, delivery, and quality.
• How do you mentor developers and establish coding standards, code review processes, and architecture governance?

Pre-Screening Video Interview Questions for Senior .NET Developer

These pre-screening interview questions are ideal for one-way video interviews on ScreeningHive. Use them to evaluate technical fit, communication skills, and problem solving before scheduling live interviews. They work well as pre-screening interview questions and video interview questions to speed hiring.

1. Describe a recent .NET project you led and your role in its architecture and delivery.

   This question evaluates experience depth, ownership, and ability to communicate technical decisions.

2. Explain how you troubleshoot a memory leak in a .NET application and which tools you would use.

   This assesses problem solving, familiarity with profiling tools, and understanding of memory management.

3. Walk through how you secure APIs and sensitive data in a .NET web application.

   This checks knowledge of authentication, authorization, encryption, and security best practices.

4. Provide an example of a performance optimization you implemented and its measurable impact.

   This reveals ability to measure, implement optimizations, and demonstrate results.

5. How do you ensure code quality and maintainability across a .NET team working on multiple services?

   This evaluates leadership, process, testing strategies, and standards for long-term code health.

Conclusion

Using a structured set of Senior .NET Developer interview questions helps hiring teams and candidates focus on the skills and scenarios that matter most in IT. Clear, role-specific questions reduce bias and speed the selection process.

ScreeningHive supports efficient hiring with one-way video interviews, faster screening, and standardised evaluations to compare candidates consistently.