Dot NET Core

Here's a list of .NET Core interview questions and answers that are commonly asked for a senior developer role. These questions cover various aspects of .NET Core, including its features, architecture, best practices, and more.

**1. What is .NET Core?**
NET Core is an open-source, cross-platform framework developed by Microsoft for building modern, high-performance applications. It supports multiple platforms, including Windows, Linux, and macOS.

**2. What are the key features of .NET Core?**
NET Core offers features like cross-platform support, high performance, modular architecture, cloud integration, ASP.NET Core for web applications, and support for microservices architecture.

**3. Explain the difference between .NET Framework and .NET Core.**
NET Framework is Windows-only and is used for building Windows applications, while .NET Core is cross-platform and can be used to build applications for Windows, Linux, and macOS.

**4. What is ASP.NET Core?**
ASP.NET Core is a cross-platform framework for building modern, cloud-based, and internet-connected applications. It's used for developing web applications and APIs.

**5. What is Dependency Injection in .NET Core, and why is it important?**
Dependency Injection (DI) is a technique where a class receives its dependencies from an external source rather than creating them internally. It promotes loose coupling, testability, and maintainability.

**6. How is configuration managed in .NET Core?**
In .NET Core, configuration is typically managed through the `appsettings.json` file. This JSON file can contain settings and connection strings that can be accessed by the application.

**7. Explain Middleware in ASP.NET Core.**
Middleware in ASP.NET Core is a pipeline of components that process requests and responses. Middleware components can handle tasks like authentication, logging, routing, and more.

**8. What is Entity Framework Core?**
Entity Framework Core is an Object-Relational Mapping (ORM) framework for .NET Core. It simplifies database interactions by allowing developers to work with databases using C # objects.

**9. What is the difference between Entity Framework Core and Entity Framework (EF6)?**
Entity Framework Core is a lightweight, cross-platform version of Entity Framework, designed to work with .NET Core and .NET 5+. EF6 is the previous version of Entity Framework that works with the full .NET Framework.

**10. Explain the concept of Middleware in ASP.NET Core.**
Middleware in ASP.NET Core is a series of components that process HTTP requests and responses in a pipeline. Each middleware component can perform specific tasks, such as authentication, routing, logging, etc.

**11. How does .NET Core handle multi-threading and concurrency?**
NET Core provides various libraries and features to handle multi-threading and concurrency, including the Task Parallel Library (TPL), async/await pattern, and concurrent collections.

**12. What is Kestrel in the context of ASP.NET Core?**
Kestrel is a cross-platform, lightweight web server built specifically for hosting ASP.NET Core applications. It's often used in combination with a reverse proxy server like Nginx or IIS.

**13. What is the purpose of the `Startup` class in ASP.NET Core?**
The `Startup` class is used to configure services, middleware, and the application's request pipeline. It's the entry point where various configurations are defined.

**14. How can you secure an ASP.NET Core application?**
You can secure an ASP.NET Core application by implementing authentication and authorization using features like Identity Framework, JWT (JSON Web Tokens), OAuth, and role-based access control.

**15. How can you deploy a .NET Core application?**
NET Core applications can be deployed using various methods, including self-contained deployment (packing the runtime with the application), publishing as a framework-dependent application, Docker containers, and cloud platforms like Azure and AWS.

These questions provide a solid foundation for discussing .NET Core concepts during an interview. Be sure to complement your understanding with practical examples and your experience working on real-world projects.

Q. When does Garbage collection occur?

A. Garbage collection occurs when one of the following conditions is true:

- The system has low physical memory.

- The memory that is used by allocated objects on the managed heap surpasses an acceptable threshold. This threshold is continuously adjusted as the process runs.

- The GC.Collect method is called and in almost all cases, you do not have to call this method, because the garbage collector runs continuously. This method is primarily used for unique situations and testing.

Q. Explain a simple GC implementation?

A. It is an excellent basis for the development of your own Garbage Collection mechanism. It provides the necessary functionality to make runtime work properly and you can build on top of that.

It may be interesting for special use cases like very short living applications or such that almost no allocate memory (you can come up with those concepts as No-alloc or Zero-alloc programming). In such a case providing GC overhead is unnecessary and it may be wise to get rid of it. It is like making huge GC.TryStartNoGCRegion overall your application.

Q. What is Zero Garbage Collectors?

A. Zero Garbage Collectors is the simplest possible implementation that in fact does almost nothing. It only allows you to allocate objects because this is obviously required by the Ex*****on Engine. Created objects are never automatically deleted and theoretically, no longer needed memory is never reclaimed.

Q. What is CTS?

A. The Common Type System (CTS) standardizes the data types of all programming languages using .NET under the umbrella of .NET to a common data type for easy and smooth communication among these .NET languages. CTS is designed as a singly rooted object hierarchy with System.Object as the base type from which all other types are derived. CTS supports two different kinds of types:

Value Types: Contain the values that need to be stored directly on the stack or allocated inline in a structure. They can be built-in (standard primitive types), user-defined (defined in source code) or enumerations (sets of enumerated values that are represented by labels but stored as a numeric type).

Reference Types: Store a reference to the value‘s memory address and are allocated on the heap. Reference types can be any of the pointer types, interface types or self-describing types (arrays and class types such as user-defined classes, boxed value types and delegates).

Q. What are some characteristics of .NET Core?

A.
Flexible deployment: Can be included in your app or installed side-by-side user- or machine-wide.

Cross-platform: Runs on Windows, macOS and Linux; can be ported to other OSes. The supported Operating Systems (OS), CPUs and application scenarios will grow over time, provided by Microsoft, other companies, and individuals.

Command-line tools: All product scenarios can be exercised at the command-line.

Compatible: .NET Core is compatible with .NET Framework, Xamarin and Mono, via the .NET Standard Library.

Open source: The .NET Core platform is open source, using MIT and Apache 2 licenses. Documentation is licensed under CC-BY. .NET Core is a .NET Foundation project.

Supported by Microsoft: .NET Core is supported by Microsoft, per .NET Core Support

Q. What Is The Purpose Of Usedeveloperexceptionpage()?

A. This method belongs to the Microsoft.AspNetCore.Builder namespace of USEDeveloperExceptionPage Extensions static class. The purpose of this function is to capture synchronous and asynchronous System.Exception instances from the pipeline and generates HTML error responses. It returns a reference to the app after the operation is completed.We use the UseDeveloperException() extension method to render the exception during the development mode.

Q. What Is The Purpose Of Useiisintegration?

A. UseIISIntegration configures the port and base path the server should listen on when running behind AspNetCoreModule. The app will also be configured to capture startup errors. WebHostBuilder uses the UseIISIntegration for hosting in IIS and IIS Express.

Q. What Is The Purpose Of Webhostbuilder() Function?

A. It is use to build up the HTTP pipeline via webHostBuilder.Use() chaining it all together with WebHostBuilder.Build() by using the builder pattern. It is available within the Microsoft.AspNet.Hosting namespace.The purpose of the Build method is to build the required services and a Microsoft.AspNetCore.Hosting.IWebHost which hosts a web application.

Q. How to create a service, register and access?

A.

1. Create a service:

public class TotalUsers
{
public long TUsers()
{
Random rnd = new Random();
return rnd.Next(100, int.MaxValue);
}
}
This class has one public method – Tusers() which returns the total number of users registered in the application.

2. Register the service:

Next add the following codes inside the ConfigureServices() method:

services.AddSingleton();
The services.AddSingleton(); will add the service which can now be shared all thought the application.

3. Access the service:

private TotalUsers totalUsers;
public HomeController(TotalUsers tu)
{
totalUsers = tu;
}

public string Index()
{
return "Total Users are: " + totalUsers.TUsers();
}

The controller has a constructor which has our service class (TotalUsers) in its parameter. When ASP.NET calls this controller it sees that the constructor requires an object of the service class (TotalUsers). MVC then goes to the Startup class and finds the TotalUsers class been configured as a service.