Access in code: builder.Configuration["ConnectionStrings:Default"]; ✅ Stored securely under your user profile (not in the project folder). 🌍 5. How do you use environment variables?

Short answer: Environment variables are great for overriding settings at deployment time (especially in Docker or Azure). Example: set ASPNETCORE_ENVIRONMENT=Production set ConnectionStrings__Default="Server=mydb;Database=App;User=sa;Passwor d=123" Notice the double underscores __ for nested keys. {

Example code

private readonly IWebHostEnvironment _env;
public HomeController(IWebHostEnvironment env)
{
_env = env;
}
public IActionResult Index()
{
if (_env.IsDevelopment())
return Content("Running in Development mode");
return Content($"Environment: {_env.EnvironmentName}");
}
} You can also access it in Program.cs: if (builder.Environment.IsProduction())
{ // Configure production services } 🧾 8. How to use different appsettings.json files? ASP.NET Core supports environment-specific JSON files. Example structure: ppsettings.json ppsettings.Development.json ppsettings.Staging.json ppsettings.Production.json Program.cs: builder.Configuration .AddJsonFile("appsettings.json") .AddJsonFile($"appsettings.{builder.Environment.EnvironmentName}.jso n", optional: true); t runtime, only the file matching the current environment will override base settings. Example: ppsettings.json { "AppName": "MyApp", "LogLevel": "Information" } ppsettings.Production.json { "LogLevel": "Error" } Result in Production → LogLevel = Error. 🔄 9. How to reload configuration dynamically? You can make JSON configuration files auto-reload when changed. Example: builder.Configuration.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true); If you update appsettings.json, the new values are reflected automatically in your app without restarting. You can subscribe to changes using IOptionsMonitor (see below). 📦 10. How to bind configuration to POCO classes? You can map sections of your configuration directly to C# classes (POCOs). Example: ppsettings.json { "AppSettings": { "SiteName": "TechStore", "PageSize": 20, "EnableCache": true }
} Create a POCO: public class AppSettings
{
public string SiteName { get; set; }
public int PageSize { get; set; }
public bool EnableCache { get; set; }
} Bind configuration: builder.Services.Configure<AppSettings>( builder.Configuration.GetSection("AppSettings")); Inject it into a controller: public class HomeController : Controller
{
private readonly AppSettings _settings;
public HomeController(IOptions<AppSettings> options)
{
_settings = options.Value;
}
public IActionResult Index()
{
return Content($"Welcome to {_settings.SiteName}!");
}
} You can also use IOptionsSnapshot for per-request reload or IOptionsMonitor for live updates. Web APIs & REST

Real-world example (ShopNest)

ShopNest admin screens use MVC: controller loads data, Razor view renders HTML, Tag Helpers build forms safely.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.