Top .NET Developer Interview Questions

Introduction

Hiring the right .NET Developer is critical for Information Technology teams that rely on stable, scalable, and secure applications. A strong hire reduces technical debt and accelerates delivery across web, desktop, and cloud platforms.

This guide provides structured interview material for screening and evaluating .NET Developer candidates. It includes basic, intermediate, and advanced questions plus a set of pre-screening one-way video interview prompts ideal for use on ScreeningHive.

.NET Developer Interview Questions

Basic .NET Developer Interview Questions

• What is the Common Language Runtime (CLR) and how does it relate to managed code?
• Explain the difference between value types and reference types in .NET. Give examples.
• What are assemblies and what role does the Global Assembly Cache (GAC) play?
• Describe how garbage collection works in .NET and when you might need to intervene.
• What is the difference between compilation and Just-In-Time compilation?
• Explain the purpose of namespaces and the difference between an interface and an abstract class.
• How does async and await work in C# and when should you use Task versus Task?
• What are the main differences between ASP.NET Web Forms, ASP.NET MVC, and ASP.NET Core?

Intermediate .NET Developer Interview Questions

• Describe your approach to handling unhandled exceptions in an ASP.NET Core web API. What techniques would you apply for consistent error responses?
• How do you implement dependency injection in an ASP.NET Core application and how do you choose between transient, scoped, and singleton lifetimes?
• Give examples of how you would optimize Entity Framework Core queries to reduce database load and improve response time.
• If you need to migrate a legacy .NET Framework application to .NET Core, what are the key steps and compatibility concerns you would evaluate?
• Explain how you would safely implement multithreading or parallel processing in a .NET service to handle CPU bound and IO bound tasks.
• Design a RESTful API endpoint for a resource with filtering, sorting, and pagination. What status codes and conventions do you use?
• Discuss caching strategies you might use in a .NET application to improve performance and how you would handle cache invalidation.
• What logging and monitoring approach would you implement for a production .NET application to ensure observability?
• Describe a CI/CD pipeline for building, testing, and deploying a .NET application. Which automated checks are most important?
• How do you secure sensitive configuration and secrets in a .NET application deployed to cloud infrastructure?

Advanced .NET Developer Interview Questions

• How would you design a microservices architecture using .NET technologies for a large-scale application? Discuss service boundaries and communication patterns.
• Describe your process for diagnosing and resolving a memory leak or high CPU utilization in a .NET application running in production.
• Explain the impact of the Large Object Heap and how you would mitigate fragmentation and GC pauses in high throughput services.
• What strategies would you use to ensure high availability and horizontal scalability for a .NET-based service under heavy load?
• Discuss indexing and partitioning strategies for a relational database accessed by .NET services and trade-offs between normalization and denormalization.
• Explain concurrency control approaches, including optimistic and pessimistic concurrency, and when to apply each in a .NET system.
• How do you apply threat modeling and secure design principles to a .NET application to protect against common web vulnerabilities?
• Describe how you would implement observability across distributed .NET services, including tracing, metrics, and centralized logging.
• When rolling out breaking changes across multiple services, how would you coordinate versioning, backward compatibility, and feature flags?
• As a technical lead, how do you run effective code reviews, mentor junior developers, and drive architecture decisions for .NET projects?

Pre-Screening Video Interview Questions for .NET Developer

These questions are tailored for one-way video interviews on ScreeningHive. They help screen technical ability, communication, and cultural fit before live interviews.

1. Please introduce your experience with .NET and describe a recent project you owned end-to-end.

   This evaluates overall experience, communication clarity, and ownership level.

2. Explain a performance problem you diagnosed in a .NET application and the steps you took to resolve it.

   This checks problem solving, familiarity with profiling techniques, and impact assessment.

3. Describe how you would implement secure authentication and authorization in an ASP.NET Core API.

   This measures understanding of security best practices, token strategies, and practical implementation choices.

4. Walk through how you structure unit and integration tests for a new feature in a .NET solution.

   This evaluates test strategy, automation mindset, and ability to ensure code quality.

5. Share a time you disagreed with a technical decision. How did you present your view and what was the outcome?

   This assesses communication, collaboration, and conflict resolution skills.

Conclusion

This set of .NET Developer interview questions helps hiring teams and candidates focus on the competencies that matter most across coding, architecture, and team collaboration. Use the basic, intermediate, and advanced sets to structure rounds and assess skill depth.

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