ASP.NET Core Configuration & Environments 1 — Questions and Answers
Question 1: What is the default hierarchy of configuration providers in ASP.NET Core?
- Environment variables override appsettings.json which overrides command-line
- appsettings.json → appsettings.{Env}.json → Environment variables → Command-line (last wins) (Correct answer)
- Command-line → appsettings.json → Environment variables
- appsettings.json → Command-line → Environment variables
Correct answer: appsettings.json → appsettings.{Env}.json → Environment variables → Command-line (last wins)
Later providers override earlier ones: appsettings.json → environment-specific file → env vars → command-line args.
Question 2: Which environment variable sets the current environment in ASP.NET Core?
- ASPNETCORE_ENV
- DOTNET_ENVIRONMENT
- ASPNETCORE_ENVIRONMENT (Correct answer)
- APP_ENVIRONMENT
Correct answer: ASPNETCORE_ENVIRONMENT
ASPNETCORE_ENVIRONMENT sets the hosting environment name, which determines which appsettings.{Env}.json file is loaded.
Question 3: How do you bind a configuration section to a strongly-typed class?
- Configuration.GetSection("Key").Bind(instance) (Correct answer)
- Configuration.Map<T>("Key")
- Configuration.Parse<T>("Key")
- Configuration.Cast<T>("Key")
Correct answer: Configuration.GetSection("Key").Bind(instance)
GetSection("Key").Bind(instance) or GetSection("Key").Get<T>() maps configuration values to properties of a strongly-typed class.
Question 4: What does IOptions<T> provide compared to IOptionsSnapshot<T>?
- IOptions is per-request; IOptionsSnapshot is singleton
- IOptions is singleton and does not reload; IOptionsSnapshot reloads per-request (Correct answer)
- They are identical
- IOptionsSnapshot is for validation only
Correct answer: IOptions is singleton and does not reload; IOptionsSnapshot reloads per-request
IOptions<T> is a singleton that doesn't reload; IOptionsSnapshot<T> is scoped and reflects configuration changes per request.
Question 5: Which interface provides configuration that reloads when the source file changes?
- IOptions<T>
- IOptionsSnapshot<T>
- IOptionsMonitor<T> (Correct answer)
- IConfigurationReloader<T>
Correct answer: IOptionsMonitor<T>
IOptionsMonitor<T> is a singleton that fires a change notification and provides the latest configuration when the source changes.
Question 6: How do you add a custom configuration source in ASP.NET Core?
- Override WebApplication.Configure()
- Implement IConfigurationSource and IConfigurationProvider, then call builder.Configuration.Add() (Correct answer)
- Add a [ConfigSource] attribute
- Register in appsettings.json
Correct answer: Implement IConfigurationSource and IConfigurationProvider, then call builder.Configuration.Add()
You implement IConfigurationSource to describe the source and IConfigurationProvider to load data, then add it via builder.Configuration.Add().
ASP.NET Core Configuration & Environments 1
What is the default hierarchy of configuration providers in ASP.NET Core?