# Application Lifecycle (.NET)

> Startup, Program.cs, Host builder, WebApplicationBuilder, app shutdown, hosted services

- 20 interview questions
- Junior
- [Interview Questions: .NET](https://sharpskill.dev/en/technologies/dotnet/interview-questions.md)

## 1. What is the main role of the Program.cs file in an ASP.NET Core application?

**Answer**

The Program.cs file centralizes the application startup code, including configuration of required services via Dependency Injection and definition of the request processing pipeline as middleware components. This approach consolidates all configuration in a single file, making it easier to manage and understand the app setup.

## 2. Which method to use to create a WebApplicationBuilder with default settings?

**Answer**

WebApplication.CreateBuilder() is the standard method to initialize a WebApplicationBuilder with default configurations. This method automatically configures logging, configuration (appsettings.json, environment variables), Kestrel server, and other essential settings to start a modern ASP.NET Core application.

## 3. Where to configure services required by the application before building the WebApplication?

**Answer**

The builder.Services property of WebApplicationBuilder provides access to the Dependency Injection container where all services are registered before building the application. This is the proper place to add services like AddControllers(), AddDbContext(), or any custom service with appropriate lifetimes (singleton, scoped, transient).

## 17 more questions available

- Which method to call on WebApplicationBuilder to build the application?
- In an ASP.NET Core application, which middleware should be registered first for security?

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