Top 10 Senior ASP.NET Developer Interview Questions & Answers in 2024

1. How does ASP.NET Core differ from the traditional ASP.NET framework, and why would you choose one over the other?

ASP.NET Core is a cross-platform, high-performance framework designed for modern web applications, while traditional ASP.NET is primarily Windows-based. ASP.NET Core is modular, lightweight, and supports cross-platform development, making it suitable for microservices and containerized applications.

2. Explain the role of the 'appsettings.json' file in ASP.NET Core and how configuration values are accessed.

The 'appsettings.json' file in ASP.NET Core is used for configuration settings. It allows developers to store application settings in a JSON format. Configuration values are accessed using the Configuration object, which reads values from the 'appsettings.json' file and other specified configuration sources.

3. Discuss the benefits and use cases of using ASP.NET Core middleware.

Middleware in ASP.NET Core plays a crucial role in processing requests and responses in the pipeline. Benefits include modularity, reusability, and the ability to customize the request/response handling process. Middleware can be used for authentication, logging, compression, and other aspects of request processing.

4. How would you implement role-based authorization in an ASP.NET Core application?

Role-based authorization in ASP.NET Core involves using the [Authorize] attribute along with specifying roles. Roles can be defined and assigned to users. For example:

[Authorize(Roles = "Admin")]
public IActionResult AdminDashboard()
{
    // Action logic for admin-only access
}

5. Explain the concept of dependency injection in ASP.NET Core and its benefits.

Dependency Injection (DI) in ASP.NET Core is a built-in feature that promotes loose coupling and better testability. It allows services to be injected into components, making it easier to manage dependencies. Services are registered in the DI container and can be injected into controllers, middleware, or other components.

6. How can you implement data validation in ASP.NET Core, and what are the available validation mechanisms?

ASP.NET Core supports data validation through model validation. Developers can use data annotations on model properties or implement the IValidatableObject interface for custom validation logic. Additionally, validation attributes and the ModelState object can be used to handle validation errors.

7. Discuss the use of Entity Framework Core migrations and how they help in database schema updates.

Entity Framework Core migrations enable developers to evolve the database schema over time. Migrations are used to create, update, or roll back the database schema based on changes in the application's data model. The Add-Migration and Update-Database commands are commonly used in the migration process.

8. How would you secure sensitive information, such as API keys or connection strings, in an ASP.NET Core application?

Sensitive information in ASP.NET Core can be secured using the user secrets manager during development and configuration providers in production. User secrets are stored locally during development, while configuration providers, like Azure Key Vault or environment variables, are used in production to keep sensitive information secure.

9. Explain the process of implementing caching in an ASP.NET Core application.

Caching in ASP.NET Core helps improve performance by storing frequently accessed data. Developers can implement caching using the [ResponseCache] attribute, the MemoryCache or distributed caching with services like Redis. Caching can be applied at the action level or globally.

10. How can you optimize the performance of an ASP.NET Core application, especially in a production environment?

Optimizing the performance of an ASP.NET Core application involves various strategies:

• Load Balancing: Distribute incoming requests across multiple servers.
• Content Delivery Networks (CDN): Cache and serve static content through CDNs.
• Compression: Enable response compression for reducing data transfer.
• Profiling and Monitoring: Use tools like Application Insights or Elastic Stack for monitoring and profiling.
• Asynchronous Programming: Implement asynchronous methods to improve responsiveness.

These strategies collectively contribute to a more efficient and scalable ASP.NET Core application.