Dotnet Interview Question(ASP.net Core Interview)

 1. How to return & handle large number of records in web api?

Ans: To handle large number of records in a web API, you can use pagination, streaming, or compression techniques.

• Implement pagination to retrieve records in smaller chunks Use streaming to process and return records in real-time Apply compression techniques like GZIP to reduce the size of the response Consider caching strategies to improve performance

2. Why should use entity framework rather than writing sql query?

Ans: Entity Framework provides a higher level of abstraction, simplifies database operations, improves productivity, and reduces code complexity. Entity Framework abstracts away the underlying database, allowing developers to work with a higher level of abstraction. It simplifies database operations by providing an object-oriented approach to data access.

• Entity Framework improves productivity by reducing the amount of code needed to perform database operations. It reduces code complexity by automatically generating SQL queries based on LINQ expressions. Entity Framework supports automatic change tracking, making it easier to handle database updates and concurrency. It provides a rich set of features like caching, lazy loading, and query optimization. Entity Framework supports multiple database providers, allowing developers to switch between different databases without changing code. It provides a seamless integration with other .NET technologies and frameworks like ASP.NET Core and MVC.

• Entity Framework Code First approach allows developers to define the database schema using C# or VB.NET classes. It supports database migrations, making it easier to evolve the database schema over time.

3. What is dependency injection and life cycle methods?

Ans: DI is a design pattern that allows objects to be loosely coupled by providing their dependencies externally. Dependency injection is a way to achieve inversion of control in software development. It helps in creating loosely coupled and modular code. In dependency injection, the dependencies of a class are provided externally rather than being created within the class itself. This allows for easier testing, maintainability, and flexibility in the codebase. There are different types of dependency injection: constructor injection, property injection, and method injection. Life cycle methods are used to manage the creation and destruction of objects in a dependency injection container.

• Common life cycle methods include: Singleton, Transient, and Scoped. Singleton creates a single instance of an object throughout the application. Transient creates a new instance of an object every time it is requested. Scoped creates a new instance of an object within a specific scope, such as a web request.

4. Where to use generic concept in your project?

Ans: Generics can be used in projects to create reusable code that can work with different types.

• Generics can be used in data structures like lists, dictionaries, and queues to store and retrieve different types of data. Generics can be used in algorithms and functions to work with different types of inputs and outputs. Generics can be used in database operations to handle different types of data.

• Generics can be used in user interfaces to create generic controls that can work with different types of data. Generics can be used in dependency injection to create generic services that can be used by different types of components.

5. How to improving your web api performance?

Ans: Improving web API performance involves optimizing code, caching, using asynchronous programming, and scaling infrastructure. Optimize code by reducing unnecessary database queries, using efficient algorithms, and minimizing network calls. Implement caching to store frequently accessed data and reduce the load on the server. Use asynchronous programming to handle multiple requests concurrently and improve responsiveness. Scale infrastructure by adding more servers, using load balancers, and optimizing database performance. Consider using a content delivery network (CDN) to cache static content and reduce latency.

6. Difference between scoped , transient and singleton?

Ans: Scoped, transient and singleton are three different lifetimes for services in .NET Core. Scoped services are created once per request and are disposed at the end of the request. Transient services are created each time they are requested. Singleton services are created once and are reused throughout the lifetime of the application. Use scoped services for components that are request-specific, transient services for lightweight stateless components, and singleton services for stateful components that should be shared across the application. Example: DbContext should be registered as a scoped service, while a logger should be registered as a singleton service.

7.  Explain how to do dependency injection?

Ans: Dependency injection is a design pattern used to inject dependencies into a class or method.

• Create an interface for the dependency

• Create a class that implements the interface

• Register the class with the dependency injection container

• Inject the dependency into the class or method

• Use the dependency in the class or method

8. What is the use of delegates?

Ans: Delegates are used to create references to methods, allowing methods to be passed as parameters or stored as variables.

• Delegates provide a way to achieve callback functionality in C#.

• Delegates can be used to implement event handling.

• Delegates enable loose coupling and separation of concerns.

• Delegates can be used to create and invoke anonymous methods.

• Delegates can be used to implement the observer pattern.

9. How to secure your web api?

Ans: Securing a web API involves implementing authentication, authorization, and encryption.

• Implement authentication to verify the identity of the client accessing the API

• Implement authorization to control what actions the client can perform

• Use HTTPS to encrypt the communication between the client and the API

• Implement rate limiting to prevent abuse and protect against denial-of-service attacks

• Apply input validation and output encoding to protect against common security vulnerabilities

• Consider using JWT (JSON Web Tokens) for authentication and authorization

• Implement logging and monitoring to detect and respond to security incidents

10. Explain the structure of the project?

Ans: The project structure in Dot Net Core typically consists of folders for source code, configuration files, and dependencies. The source code is usually organized into folders based on the application's modules or layers, such as Controllers, Models, and Views.

• Configuration files like appsettings.json store application settings and connection strings.

• Dependencies are managed using a package manager like NuGet, and their versions are specified in the project file (csproj).

• The project may also include folders for tests, documentation, and build scripts.

• Example: The Controllers folder contains classes that handle HTTP requests and define the application's API endpoints.

11. Write join query using entity framework?

Ans: Join query using Entity Framework

• Use the LINQ query syntax to perform joins in Entity Framework

• Use the 'join' keyword to specify the join condition

• Use 'into' keyword to create a group join

• Use 'on' keyword to specify the join condition

• Use 'equals' keyword to define the equality condition

12. Difference between generic and delegates

Ans: Delegates are function pointers used to encapsulate methods, while generics are used to create reusable code for different data types.

• Delegates are used to create callbacks and event handlers.

• Generics allow the creation of classes, methods, and interfaces that can work with different data types.

• Delegates can be used to define and invoke methods dynamically at runtime.

• Generics provide type safety and eliminate the need for boxing and unboxing operations.

• Delegates can be multicast, allowing multiple methods to be invoked with a single delegate.

• Generics improve code reusability and performance by avoiding unnecessary type conversions.

13. WAP to reverse a string letters

Ans: A program to reverse the letters of a given string.

• Create an empty string to store the reversed string

• Iterate through the original string from the end to the beginning

• Append each character to the empty string

• Return the reversed string

14. Design patterns. Explain any one?

Ans: Factory pattern. Creates objects without exposing the instantiation logic to the client.

• Defines an interface for creating objects, but lets subclasses decide which classes to instantiate.

• Client only knows the abstract type, not the concrete type.

• Used when a class cannot anticipate the type of objects it must create.

• Examples: Abstract Factory, Singleton, Builder, Prototype.

15. WAP to find the prime number

Ans: WAP to find the prime number

• Loop through numbers and check if divisible by any number less than it

• Exclude 1 and the number itself

• 2 is the only even prime number

16. What are the different ways of rendering a Partial View in ASP.NET MVC?

Ans: In ASP .Net MVC, four methods help in rendering a partial view.  

The four methods include:

•  RenderPartial: Using this technique, a partial view contained within another view is directly rendered. Instead of giving back a string, it just publishes the partial view to the output stream.
   
• RenderAction: With the help of this technique, you can render a partial view by calling a controller action. When you wish to run controller logic before to rendering the partial view, this is helpful.
   
• Partial: A partial view is rendered using this technique inside another view. The displayed content is returned as a string, which you can then use in your view.
   
• Action helper: By calling a controller action from within your main view, you can render a partial view using the Action Helper method.

17. What are the different return types used by the controller action method in MVC?

Ans: 

In ASP.NET MVC, controller action methods are in charge of managing incoming requests, carrying out required processing, and providing the client with a response. Depending on the kind of answer that a controller action method needs to produce, it can have a variety of return kinds. The following are typical return types used by MVC controller action methods:

• ViewResult
• PartialViewResult
• JsonResult
• RedirectResult 
• RedirectToRouteResult 
• FileResult 
• ContentResult
• EmptyResult

18. Explain the difference between a user control and a custom control in ASP.NET.
Ans:

A user control is a reusable UI component that is specific to a single application and can contain both HTML and server side code. It is saved as an .ascx file and can be used multiple times on a single page. A custom control, on the other hand, is a reusable component that can be used across multiple applications. It is compiled as a .dll file and can be added to the Toolbox to be used on any page or form.