Top 15 .NET Core Interview Questions and Answers [UPDATED 2025] – Expert Guide

Why .NET Core Skills Are Essential in 2025

.NET Core has rapidly evolved into a cornerstone technology for building scalable, high-performance applications across cloud, web, and enterprise domains. In 2025, its demand is stronger than ever, powered by new features in .NET 7 and .NET 8, cloud-native capabilities, and robust support for microservices, minimal APIs, and secure architectures. Whether you’re a fresher or a senior developer, mastering .NET Core is your gateway to lucrative roles at top companies worldwide.

Overview: What Interviewers Really Want in .NET Core Candidates

• Deep understanding of .NET Core architecture – including dependency injection, middleware, and hosting models
• Hands-on experience with modern features – minimal APIs, gRPC, cloud-native design
• Problem solving using real-world scenarios – debugging, scaling, and securing enterprise apps
• Teamwork and communication – ability to explain choices and collaborate on architecture
• Continuous learning – up-to-date on .NET 8+ and adjacent tech (Kubernetes, Blazor, AI integration)

Let’s explore the top 15 .NET Core interview questions and answers that will help you stand out in your next technical interview.

💡 Key Takeaway

Always intertwine practical examples and scenario-based answers with theory. Interviewers want to see how you apply your knowledge to solve real problems – not just textbook definitions!

Top 15 .NET Core Interview Questions & Answers for 2025

1. What is .NET Core, and how does it differ from .NET Framework?
   Answer: .NET Core is a cross-platform, open-source framework for building modern, cloud-based, and high-performance applications. Unlike the traditional .NET Framework, .NET Core runs on Windows, Linux, and macOS, supports microservices and containers, and is modular via NuGet packages. .NET 5 and onward unify .NET Core and .NET Framework into “.NET”.
2. How does Dependency Injection work in .NET Core?
   Answer: Dependency Injection (DI) in .NET Core is built-in and configured via the IServiceCollection. Services can be registered as Singleton, Scoped, or Transient lifetimes. DI decouples classes from concrete implementations, making code more testable and maintainable.
3. Explain the Middleware pipeline in ASP.NET Core.
   Answer: Middleware are software components assembled into an application pipeline to handle requests and responses. Each middleware can perform actions before and after calling the next. Common examples: authentication, routing, error handling, static file serving.
4. What are Minimal APIs in .NET 6/7/8?
   Answer: Minimal APIs allow you to create HTTP APIs with minimal setup, using fewer files and less boilerplate code. It’s ideal for microservices, rapid prototyping, and functions-as-a-service. Example:

   var app = WebApplication.CreateBuilder(args).Build();
   app.MapGet("/hello", () => "Hello, World!");
   app.Run();

5. How do you implement Authentication and Authorization in ASP.NET Core?
   Answer: Use ASP.NET Core Identity for managing users, roles, and claims. Integrate JWT tokens for APIs, and configure policies for fine-grained access control. Key steps: register Identity services, configure authentication schemes, and decorate controllers/actions with [Authorize] attribute.
6. Describe the role of Configuration and Options pattern in .NET Core.
   Answer: The Options pattern uses strongly typed classes to bind app settings from configuration sources (appsettings.json, environment variables, secrets). This provides type safety and easier management for complex configurations.
7. How do you handle logging and diagnostics?
   Answer: ASP.NET Core supports built-in logging via Microsoft.Extensions.Logging. Plug in providers for console, file, Application Insights, or third-parties like Serilog. Leverage structured logging, correlation IDs, and distributed tracing for production readiness.
8. What is Entity Framework Core, and how do you use it?
   Answer: EF Core is Microsoft’s ORM for .NET. It supports LINQ queries, change tracking, migrations, and multiple database providers. Typical steps: define DbContext and POCOs, configure services, use migrations for schema changes, and query/update data with LINQ.
9. Explain how to handle caching and improve performance.
   Answer: Use in-memory caching (IMemoryCache), distributed caching with Redis, and response caching middleware. For high-scale apps, offload caching from the app server, and set cache expiration and eviction policies.
10. How do you build and deploy microservices with .NET Core?
    Answer: .NET Core is ideal for microservices due to its lightweight nature and containerization support. Use Docker to containerize services, orchestrate with Kubernetes, and communicate via REST, gRPC, or messaging (RabbitMQ, Azure Service Bus). Ensure services are stateless and independently deployable.
11. What are the best practices for securing .NET Core applications?
    Answer:
    • Use HTTPS and HSTS
    • Validate input and sanitize output
    • Implement robust authentication & authorization
    • Store secrets securely (Azure Key Vault, environment variables)
    • Regularly patch dependencies
12. How do you troubleshoot memory leaks and performance bottlenecks?
    Answer: Use tools like dotMemory, PerfView, and Visual Studio Diagnostics. Profile allocations, monitor garbage collection, and analyze call stacks. In code, ensure you dispose objects properly and avoid static references that prevent GC.
13. What’s new in .NET 8 (2025) that every developer should know?
    Answer: Improved performance, hot reload for APIs, enhanced System.Text.Json, better cloud-native integration, more efficient minimal APIs, and new tools for distributed tracing and diagnostics are highlights in .NET 8.
14. How do you use asynchronous programming and ensure thread safety?
    Answer: Use async/await, Task, and ValueTask for non-blocking I/O. For thread safety, use immutable data structures, locks, and the Concurrent collections when sharing data between threads.
15. How do you integrate AI/ML or third-party APIs in .NET Core?
    Answer: Leverage libraries like ML.NET for in-app ML, or call external APIs (REST/gRPC) using HttpClient or gRPC client. Secure integrations with keys and robust error handling. Consider using Azure Cognitive Services or OpenAI for advanced scenarios.

💡 Pro Tip

When answering scenario questions, break your response into: 1) What the challenge is, 2) The tools/features you’d use, 3) Why you chose them, and 4) The outcome or benefit. This structure impresses interviewers every time!

Scenario-Based .NET Core Interview Questions (With Sample Answers)

1. Scenario: Your .NET Core API is slowing down under heavy traffic.
   Sample Answer: Analyze bottlenecks with Application Insights and distributed tracing. Implement caching for frequent queries, use async endpoints, enable response compression, and scale out with Kubernetes. Always monitor performance counters and logs.
2. Scenario: Users report sporadic authentication failures.
   Sample Answer: Check Identity configuration, ensure token lifetimes are consistent, monitor for clock skew, and validate middleware order. Review logs for exceptions, and test with multiple environments to reproduce the issue.
3. Scenario: You’re tasked with migrating a legacy .NET Framework app to .NET 8.
   Sample Answer: Assess dependencies for compatibility, rewrite config files, migrate to modern authentication/authorization, leverage migration tools, and set up CI/CD pipelines. Incrementally validate with integration and unit tests.

Tip: For more scenario questions, check out our Asp Net Interview Questions And Answers.

💡 Key Takeaway

Demonstrate up-to-date knowledge by referencing new .NET 8 features and explaining how you’d apply them to solve current business challenges.

Watch: .NET Core Interview Questions Walkthrough (2025)

Prefer visual learning? This concise YouTube video covers the latest .NET 8 questions with clear explanations and is perfect for quick pre-interview revision.

Quick Reference Table: .NET Core Key Concepts and Features

How to Ace Your .NET Core Interview: Practical Tips

• Practice speaking your answers out loud – This builds confidence and highlights gaps.
• Pair up for mock interviews – Use platforms like Huru.ai for unlimited AI-powered practice with instant feedback.
• Showcase relevant projects – Be ready to discuss not just what you built, but why you made specific design choices.
• Stay current – Reference .NET 8 features, DevOps, and security best practices for 2025.
• Review related roles and questions: Kubernetes Interview Questions Answers | Asp Net Interview Questions And Answers | Network Engineer Interview Questions Navigate The Technical Terrain 2

💡 Final Words

Commit to regular, focused practice and leverage platforms like Huru to accelerate your growth. Employers value real-world skills, communication, and a drive for continuous learning. Go in prepared, and you’ll stand out in any .NET Core interview in 2025!

Elias Oconnor is a senior content writer at Huru.ai, specializing in career growth, technical interview prep, and AI-driven job search solutions. With years of experience in the tech recruitment space, Elias is dedicated to guiding candidates to success through actionable advice and industry insights.