📌 Series Context: This is the fifth article in the 10‑part series covering the most important areas of .NET interview preparation. In Part 1, we introduced the .NET ecosystem. In Part 2, we covered C# fundamentals.In Part 3, we explored advanced C# features. In Part 4, we discussed ASP.NET MVC. Now, we’ll focus on ASP.NET Core, the modern, cross‑platform successor to MVC.

Why ASP.NET Core?

ASP.NET Core is a cross-platform, high-performance, open-source framework for building modern web applications and APIs. It's designed to run on Windows, Linux, and macOS, making it ideal for cloud-native development.

Interviewers often ask about middleware, dependency injection, configuration, and hosting in ASP.NET Core.

Key Features

Cross-Platform

Unified Framework

Middleware Pipeline

Dependency Injection

Configuration

Middleware Pipeline

ASP.NET Core uses middleware components to process HTTP requests.

Example

public void Configure(IApplicationBuilder app)
{
    app.UseRouting();

    app.UseAuthentication();

    app.UseAuthorization();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });
}

👉 Interview Tip: Be ready to explain the order of middleware execution.

Dependency Injection

ASP.NET Core has built-in dependency injection. Services are registered in Startup.cs.

Example

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers();

    services.AddScoped<IPatientService, PatientService>();
}

👉 Interview Tip: Be ready to explain Scoped vs Singleton vs Transient lifetimes.

Configuration

ASP.NET Core supports multiple configuration sources:

Example

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=.;Database=HospitalDB;Trusted_Connection=True;"
  }
}

Hosting

ASP.NET Core applications are hosted using Kestrel (the built-in web server).

They can also be reverse-proxied with:

Common Interview Questions (Part 5)

Conclusion

In this fifth part, we covered:

This foundation prepares you for Part 6, where we'll explore Entity Framework & Data Access—covering LINQ, migrations, and performance tips.

Summary

ASP.NET Core is a modern, cross-platform framework designed for building high-performance web applications and APIs. Understanding its middleware pipeline, dependency injection system, configuration sources, hosting options, and service lifetimes is essential for both real-world development and .NET interview preparation.