What is .NET Core?
💡 Concept Name
.NET Core
📘 Quick Intro
.NET Core is a free, open-source framework developed by Microsoft. It allows developers to build cross-platform apps for Windows, Linux, and macOS. It's known for its performance, flexibility, and support for modern web development.
🧠 Analogy / Short Story
Imagine building a car that only works on one road—frustrating, right? That's how traditional platforms worked. .NET Core is like building a car that drives on all roads—highways, city roads, or even hills—because it works across all operating systems. One framework, everywhere.
🔧 Technical Explanation
.NET Core is a lightweight, modular, and cross-platform framework used to develop cloud-ready and high-performance apps. It supports C#, F#, and VB.NET and can be used to create web apps, APIs, desktop apps, and microservices.
It uses a built-in dependency injection system and supports modern features like minimal APIs, async/await, and middleware. Unlike the legacy .NET Framework, .NET Core apps can be deployed as self-contained or framework-dependent binaries.
🎯 Purpose & Use Case
- ✅ Build apps that run on Windows, Linux, and macOS
- ✅ Create microservices and high-performance web APIs
- ✅ Containerize apps using Docker
- ✅ Integrate easily with DevOps pipelines
- ✅ Build scalable, cloud-based enterprise apps
💻 Real Code Example
Minimal Web API in .NET Core:
// Program.cs
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers();
var app = builder.Build();
app.MapControllers();
app.Run();
Key Highlight: This uses .NET Core’s built-in DI and routing. No extra setup needed—ideal for microservices.
❓ Interview Q&A
Q1: What is .NET Core?
A: It's a modern, open-source framework for building cross-platform apps.
Q2: Difference between .NET Core and .NET Framework?
A: .NET Core is cross-platform; .NET Framework works only on Windows.
Q3: Languages supported by .NET Core?
A: C#, F#, and VB.NET.
Q4: Is .NET Core faster than .NET Framework?
A: Yes, it’s optimized for performance and scalability.
Q5: How does DI work in .NET Core?
A: Through the built-in service container using `AddSingleton`, `AddScoped`, etc.
Q6: Can I deploy .NET Core on Linux server?
A: Yes, it works perfectly on Linux environments.
Q7: What is the use of `Program.cs` in .NET Core?
A: It acts as the entry point for the app and sets up the pipeline.
Q8: How is ASP.NET Core related to .NET Core?
A: ASP.NET Core runs on .NET Core to build web apps and APIs.
Q9: How to install .NET Core CLI?
A: Download from Microsoft's official site or use package managers like `apt`, `brew`, or `choco`.
Q10: What replaced `Global.asax` in .NET Core?
A: Middleware and `Startup.cs` configuration pipeline.
📝 MCQs
Q1: Which of the following is true about .NET Core?
- A. Only works on Windows
- B. It is cross-platform and open-source
- C. It is a paid Microsoft product
- D. It replaces Java entirely
Q2: What is the default entry point of a .NET Core application?
- A. Startup.cs
- B. Main.cs
- C. Program.cs
- D. Init.cs
Q3: Which of the following CLI command creates a new .NET Core web app?
- A. dotnet new mvc --web
- B. dotnet create webapp
- C. dotnet new webapp
- D. dotnet build web
Q4: Which language is NOT officially supported by .NET Core?
- A. C#
- B. F#
- C. VB.NET
- D. Python
Q5: What is Kestrel in .NET Core?
- A. Logging Framework
- B. Web Server
- C. ORM Tool
- D. Authentication Middleware
Q6: Which of these is the correct command to restore NuGet packages in a .NET Core project?
- A. nuget restore
- B. dotnet restore
- C. dotnet build --restore
- D. restore-packages
Q7: What is the role of `Startup.cs` in a .NET Core web app?
- A. Runs the database migration
- B. Configures services and request pipeline
- C. Hosts the web server
- D. Compiles Razor views
Q8: Which method adds a service with per-request lifetime in .NET Core DI?
- A. AddSingleton
- B. AddScoped
- C. AddTransient
- D. AddPerRequest
Q9: Which command publishes a .NET Core app for production?
- A. dotnet run --env Prod
- B. dotnet build --prod
- C. dotnet publish --configuration Release
- D. dotnet deploy --release
Q10: What major version unified .NET Core and .NET Framework?
- A. .NET Core 5
- B. .NET 5
- C. .NET 3.1
- D. .NET Framework 4.8
💡 Bonus Insight
.NET Core evolved into .NET 5/6/7+ which unified the ecosystem. Now, you just use ".NET" — but the core benefits remain. It’s cross-platform, scalable, and ready for modern cloud workloads.
📄 PDF Download
Need a handy summary for your notes? Download this topic as a PDF!