Posted on Oct 11 • Originally published at bytehide.com Dive into the world of contemporary programming as we untangle some of the most commonly asked dotnet Core interview questions and answers!Staying up-to-date with the evolution of technology can be a demanding task, but not if you’re provided with clear explanations and useful insights. In this chunk of knowledge, we’ll delve deeply into the key aspects of .Net Core, allowing you to showcase your expertise and ace your next interview.Whether you’re an aspiring programmer or an experienced developer revisiting your core dotnet interview know-how, this right here is your invaluable resource!In .NET Core, Dependency Injection (DI) is a technique whereby one class (or module) outsources the creation of its dependencies to an external framework instead of handling them itself.Built-in DI is a significant aspect of .NET Core. It comes with integrated support for dependency injection, unlike the previous versions, where we had to rely on external libraries like AutoFac, Ninject, Unity, etc.Here is a simple example:In this case, SampleClassA depends on ISampleClassB. To inject ISampleClassB into SampleClassA, you need to register these classes in your Startup.cs file:When SampleClassA is created, .NET Core automatically creates an instance of SampleClassB and injects it into the constructor.In terms of performance, both .NET Core and Node.js have their strengths and weaknesses. Performance can also be relative based on the specific workload and requirements of the application, but here are some general insights:Remember, while these are some of the general observations, the real-life performance of an application will depend on various factors, including how well the code is written and optimized..NET Core projects are capable of targeting multiple platforms including Windows, Linux, and macOS. This can be managed through the project file (*.csproj).First, the Target Framework Moniker (TFM) determines the APIs that you have access to. It is possible to specify multiple target frameworks and libraries depending on your application needs. The selected framework will dictate which APIs your code can call.Here is an example where the project targets .NET Core 3.1 and .NET Standard 2.0:You need to be aware of any breaking changes or incompatible APIs when targeting multiple platforms. It is also possible to handle divergent code with the help of preprocessor directives.Entity Framework Core (EF Core) is a lightweight, extensible, open-source, and cross-platform version of the popular Entity Framework data access technology. Here are the main advantages of using EF Core:Kestrel is a cross-platform web server built for .NET Core based applications. It is based on a libuv library, an asynchronous I/O-based model used by Node.js. Kestrel can also be used in combination with a reverse proxy server such as Apache, Nginx, or IIS, which provides an additional layer of configuration, security, and load balancing.Here are the key differences between Kestrel and other web servers such as IIS and Http.sys:Overall, when considering a web server for hosting .NET Core applications, Kestrel provides a high-performance, cross-platform, and flexible option that aligns well with the objectives of .NET Core.Moving smoothly from servers to application patterns, let’s discuss another fundamental topic that often spices up net core questions for interviews – the Repository pattern.Certainly, transitioning from the way Kestrel servers operate in .NET Core to the application of patterns in Entity Framework Core might seem like a leap. But don’t fret, as we’ll guide you through the interconnected world of .NET Core with simple explanations and concise examples.To implement the Repository pattern in a .NET Core application using Entity Framework Core, you could follow these general steps:Here is a simple example of what the repository class might look like:Global exception handling in ASP.NET Core can be achieved using middleware. The ideal place to handle exceptions is in the middleware pipeline so that it is separate from your application logic, and can trap any unhandled exceptions.One of the most effective ways is to use the built-in UseExceptionHandler middleware which captures synchronous and asynchronous exceptions. With this middleware, you can redirect to an error handling route or render an error response directly.In the above code, when an exception is raised it is handled by the “/api/Error” route.Another method of handling global exceptions is using UseDeveloperExceptionPage middleware which provides detailed exception information in the local development environment.There are a number of significant differences between .NET Core 2.x and .NET Core 3.x:Desktop Development: .NET Core 3 introduced support for Windows Desktop Applications (Windows Forms and WPF). This feature was not available in .NET Core 2.New JSON APIs: .NET Core 3.0 introduced new built-in JSON APIs that are high-performance and low allocation, making them significantly faster than JSON.NET.HTTP/2 Support: In .NET Core 3, built-in support for HTTP/2 was added.Improved performance: Continuous enhancements were made to improve the performance of .NET Core including less memory consumption and faster application startup times.gRPC Services: .NET Core 3.x introduced support for gRPC, a modern open-source high-performance RPC framework.Support for ARM64: .NET Core 3.0 added support for ARM64-based processors.Azure Active Directory (Azure AD) provides an easy way for businesses to manage identity and access, both in the cloud and on-premises. You can use it to add sign-in functionality and regulate access to your .NET Core applications. Here are the essential steps to configure and work with Azure AD in a .NET Core application:Register your application with your Azure AD tenant:Configure your .NET Core application to use Azure AD:Open your application settings in the Azure portal, copy the Directory (tenant) ID and Application (client) ID, and then use them to configure the authentication in your .NET Core application.Protect your application’s routes:Use Azure AD as user store:You can use Azure AD to store and manage users for your .NET Core application.Entity Framework Core (EF Core) includes a feature called Migrations that allows you to make changes to your model and then propagate those changes to your database schema. Here’s a basic overview of performing a migration:1. Install the necessary packages: EF Core requires certain NuGet packages to perform migrations. Make sure you have the basic Entity Framework Core and EF Core tools packages installed in your project.2. Create a new Migration: Use the Add-Migration command and provide a name for your migration. This creates a new class in your Migrations folder that contains the changes to be made to the database schema.3. Update the database: Use the Update-Database command. This applies any pending migrations on the database. EF Core creates the database if it does not exist.You may opt to provide a specific migration name if you want to update the database to a specific migration rather than the latest.Remember to treat migrations as a part of your codebase. They need to be kept under source control and applied as part of your deployment process. Well-managed migrations are key to dealing with evolving database schemas.We’ve had a comprehensive understanding of how to conduct database migrations in Entity Framework Core so far. But what about real-time communication in web applications?As the terrain of dotnet core interview questions and answers is vast and varied, let’s shift our sails and explore the realm of SignalR and its indispensable role in the .NET Core universe.Real-time communication is a crucial cog in the wheel of interactive and highly responsive applications, so stick around as we dive deeper!SignalR is a library in .NET Core used to facilitate real-time communication between server and client. It uses several techniques under the hood to maintain a persistent connection between the client and the server. This connection allows real-time communication with high-frequency updates.SignalR uses WebSockets, Long Polling, Server-Sent Events, and others to maintain this connection, choosing the best available transport method based on the client and server capabilities.In effect, SignalR simplifies the process of creating real-time, responsive web applications. It’s widely used in applications where high frequency updates are required, such as live chat, gaming, real-time dashboards, and others.IdentityServer4 is an OpenID Connect and OAuth 2.0 framework for .NET Core, which can be used to secure your .NET Core Web API.To do this, you would need to install and configure IdentityServer4 in your application. This will involve creating the necessary client configurations, defining scopes, and securing your API endpoints.Here is a basic overview of the steps:It’s important to remember that securing your API requires a clear understanding of authentication and authorization concepts, as well as the protocols used by IdentityServer4 (OpenID Connect and OAuth 2.0)..NET Core provides an elegant solution to managing configurations across different environments through the use of configuration providers.For managing configuration, you can use the appsettings.json file, which is the default file read by .NET Core application. Moreover, you can have dedicated configuration files for each environment, such as appsettings.Development.json or appsettings.Production.json, giving you the chance to override the default settings.Here are some steps you could take:Remember to exclude sensitive data like connection strings and application secrets from source control by using secure methods like user secrets or Azure Key Vault.With .NET Core, you get an in-built, easy-to-use logging API which supports a variety of built-in and third-party logging providers. It provides various logging levels like Trace, Debug, Information, Warning, Error, and Critical.The steps to add logs to a .NET Core application using this framework are as follows:You can configure these log levels and logging output targets in the appsettings.json or in your code. The framework automatically reads from the configuration settings at runtime.Command Query Responsibility Segregation (CQRS) is a pattern in which read operations (queries) and write operations (commands) are separated, improving performance, scalability, and security.To implement this in .NET Core:Remember, while CQRS can provide performance and scalability benefits, it adds complexity to the application and should be used wisely, preferentially in more complex scenarios where these benefits are significant.Having understood how to implement Command Query Responsibility Segregation (CQRS) in a .NET Core application, it’s time to transition towards microservices. The jump may seem wide, but it’s all threads in the same vast tapestry of core dotnet interview questions.In the complex world of .NET Core ecosystems, knowledge of microservices becomes incredibly pertinent. So, let’s delve into the support provided by .NET Core for the development of microservices and how they efficiently manage a large application’s complex business requirements..NET Core supports the development of microservices by several ways:There are several differences in how routing is handled in ASP.NET Core MVC compared to ASP.NET MVC.Optimizing performance in .NET Core applications could involve several techniques:Managing session state in a distributed .NET Core application generally involves either a server-side or client-side session management approach.Remember to always secure session data, especially when incorporating client-side session management strategies.Handling errors and debugging in a distributed .NET Core application with multiple microservices can be challenging. Some of the strategies include:Remember that in a microservices architecture errors should be handled at the service level. Each service should handle its own exceptions and return a suitable error message or response code.Wrapping up our deep dive into net core questions for interviews, we hope you found the thorough explanations and code examples enlightening.Remember, the journey of a thousand miles begins with a single step, and every complex problem can be broken down into simple, easy-to-understand blocks. And that’s precisely what our exploration of the .NET Core environment aimed to do.So whether you’re preparing for your next interview or simply seeking to solidify your .NET Core understanding, keep this guide in your arsenal!Until next time, happy coding!Templates let you quickly answer FAQs or store snippets for re-use. Are you sure you want to hide this comment? It will become hidden in your post, but will still be visible via the comment's permalink. 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