Interview Q&A

Short answer: SP.NET MVC 5? ASP.NET Core is a cross-platform, open-source framework for building modern web pplications, APIs, and microservices. It’s a complete rewrite of the old ASP.NET framework, designed to be lightweight, modular, and cloud-ready. Key Differences: Feature ASP.NET MVC 5 ASP.NET Core Platform Windows only Cross-platform (Windows, macOS,… Linux)……… Hosting IIS only Kestrel, IIS, Nginx, Apache, self-hosting…

Explain a bit more

Configuration web.config (XML) appsettings.json (JSON-based) Dependency Injection Third-party libraries Built-in DI container Modularity Monolithic Modular via NuGet packages Example: In ASP.NET MVC 5, you’d deploy only to IIS on Windows. {

Example code

public void ConfigureServices(IServiceCollection services)
{ services.AddControllers(); }
public void Configure(IApplicationBuilder app)
{ pp.UseRouting(); pp.UseEndpoints(endpoints => endpoints.MapControllers());
}
} 🧭 6. Explain the purpose of Program.cs in .NET 6+. In .NET 6+, Startup.cs and Program.cs merged into one minimal host configuration file. It sets up the web host, configuration, logging, and middleware pipeline. Example: var builder = WebApplication.CreateBuilder(args); builder.Services.AddControllers(); var app = builder.Build(); pp.MapControllers(); pp.Run(); It’s simpler, faster, and easier to read. Minimal APIs are a lightweight way to build small HTTP APIs without controllers or ttributes. Perfect for microservices. Example: var app = WebApplication.Create(args);
{ [HttpGet("{id}")] public IActionResult Get(int id) => Ok($"Product {id}");
} 🧩 11. What is Endpoint Routing? Endpoint routing separates route matching from execution. It lets middleware (like authentication) know which endpoint will be executed before it runs. Example: pp.UseRouting(); pp.UseAuthorization(); pp.UseEndpoints(endpoints => endpoints.MapControllers()); 🔄 12. Explain the role of middleware in ASP.NET Core. Middleware are components that handle requests and responses in a pipeline. Each can: Process requests Call the next middleware Or short-circuit the pipeline Example: logging middleware that runs before all others: pp.Use(async (context, next) => { Console.WriteLine("Request: " + context.Request.Path); wait next(); }); 🕒 13. What is the order of middleware execution? Middleware execute in the order they’re added in Program.cs. Response flows in reverse order back up the chain. Tip: Authentication must come before Authorization. UseRouting must come before UseEndpoints. 🧩 14. How to create custom middleware? Example: public class RequestLoggingMiddleware
{
private readonly RequestDelegate _next;
public RequestLoggingMiddleware(RequestDelegate next) => _next = next; public async Task Invoke(HttpContext context)
{ Console.WriteLine($"Request for: {context.Request.Path}"); wait _next(context); }
} Register it: pp.UseMiddleware<RequestLoggingMiddleware>(); 🧱 15. What is the difference between middleware and filters? Feature Middleware Filter Scope Entire app Controller/action level Runs on Every request MVC actions only Example Authentication, logging Validation, exception filters ⚒ 16. Explain the IApplicationBuilder interface. IApplicationBuilder builds the middleware pipeline. You use it in Startup.Configure() or Program.cs to add middleware via Use, Run, nd Map. 🔀 17. Difference between Use, Run, and Map in middleware. Metho Description Example Use Adds middleware that can call the next component. pp.UseMiddleware<Logging>(); Run Terminates the pipeline — no next middleware. pp.Run(async c => await c.Response.WriteAsync("End")); Map Branches pipeline based on request path. pp.Map("/admin", a => .Run(...)); 🏗 18. What are Hosting Models in ASP.NET Core (In-process vs Out-of-process)? Model Description Performance In-process App runs inside IIS worker process (w3wp.exe). Faster (single process) Out-of-proces IIS acts as reverse proxy to Kestrel. Slight overhead Example: For Windows servers, in-process gives best performance. For cross-platform Docker, use out-of-process. 🌍 19. Explain Web Host vs Generic Host. Host Type Used For Example Web Host Web apps (ASP.NET Core ≤ 2.2) WebHost.CreateDefaultBui lder() Generic Host ny app: web, worker, console (≥ 3.0) Host.CreateDefaultBuilde r() Generic Host unifies background tasks, APIs, and services in one model. ⚙ 20. How does configuration binding work in SP.NET Core? ASP.NET Core can automatically bind configuration from: appsettings.json Environment variables Command-line arguments Example: // appsettings.json { "AppSettings": { "SiteName": "MyShop", "Version": "1.0" }
} // POCO public class AppSettings
{
public string SiteName { get; set; }
public string Version { get; set; }
} // Program.cs builder.Services.Configure<AppSettings>( builder.Configuration.GetSection("AppSettings")); You can inject IOptions<AppSettings> anywhere. MVC Architecture & Controllers

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.

Short answer: dotnet publish -c Release

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.

Short answer: Install package: dotnet add package Microsoft.Extensions.Caching.StackExchangeRedis

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.

Short answer: Caching improves performance by storing frequently used data in memory or external storage to reduce database or API calls. SP.NET Core provides:

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.

Short answer: Creating REST APIs in ASP.NET Core is straightforward using controllers or minimal APIs.

Explain a bit more

Traditional Controller-Based API dotnet new webapi -n MyApi Program.cs: var builder = WebApplication.CreateBuilder(args); builder.Services.AddControllers(); var app = builder.Build(); app.MapControllers(); app.Run(); Controller: [ApiController] [Route("api/[controller]")] public class ProductsController : ControllerBase [HttpGet] public IActionResult GetAll() => Ok(new[] { "Laptop", "Phone" }); ✅ You get RESTful endpoints automatically (GET /api/products). Creating REST APIs in ASP.NET Core is straightforward using controllers or minimal APIs.

Example code

Traditional Controller-Based API dotnet new webapi -n MyApi Program.cs: var builder = WebApplication.CreateBuilder(args); builder.Services.AddControllers(); var app = builder.Build(); app.MapControllers(); app.Run(); Controller: [ApiController] [Route("api/[controller]")] public class ProductsController : ControllerBase [HttpGet] public IActionResult GetAll() => Ok(new[] { "Laptop", "Phone" }); ✅ You get RESTful endpoints automatically (GET /api/products). Creating REST APIs in ASP.NET Core is straightforward using controllers or minimal APIs. Example: Traditional Controller-Based API dotnet new webapi -n MyApi Program.cs: var builder = WebApplication.CreateBuilder(args); builder.Services.AddControllers(); var app = builder.Build(); app.MapControllers(); app.Run(); Controller: [ApiController] [Route("api/[controller]")] public class ProductsController : ControllerBase [HttpGet] public IActionResult GetAll() => Ok(new[] { "Laptop", "Phone" }); ✅ You get RESTful endpoints automatically (GET /api/products). Creating REST APIs in ASP.NET Core is straightforward using controllers or minimal APIs. Example: Traditional Controller-Based API dotnet new webapi -n MyApi Program.cs: var builder = WebApplication.CreateBuilder(args); builder.Services.AddControllers(); var app = builder.Build(); app.MapControllers(); app.Run(); Controller: [ApiController] [Route("api/[controller]")] public class ProductsController : ControllerBase [HttpGet] public IActionResult GetAll() => Ok(new[] { "Laptop", "Phone" }); ✅ You get RESTful endpoints automatically (GET /api/products). 🧱 2. What is the [ApiController] attribute? [ApiController] simplifies building APIs by adding smart defaults: Automatic model validation → 400 Bad Request on invalid models Automatic [FromBody], [FromQuery], etc. inference Follow : ProblemDetails JSON response for errors Example: [ApiController] [Route("api/[controller]")] public class OrdersController : ControllerBase [HttpPost] public IActionResult CreateOrder(Order order) if (!ModelState.IsValid) return BadRequest(ModelState); return CreatedAtAction(nameof(CreateOrder), new { id = 1 }, order); 📦 3. How does content negotiation work? Content negotiation allows clients to request responses in a specific format (JSON, XML, etc.) using the Accept header. ASP.NET Core automatically picks the best formatter: GET /api/products Accept: application/json Response → JSON GET /api/products Accept: application/xml Response → XML (if XML formatter is added) Follow : Enable XML Support: builder.Services.AddControllers() .AddXmlSerializerFormatters(); 🧭 4. How to handle versioning in APIs? You can version APIs to maintain backward compatibility using the Microsoft.AspNetCore.Mvc.Versioning package. Install: dotnet add package Microsoft.AspNetCore.Mvc.Versioning Configure: builder.Services.AddApiVersioning(options => options.DefaultApiVersion = new ApiVersion(1, 0); options.AssumeDefaultVersionWhenUnspecified = true; options.ReportApiVersions = true; }); Use in controllers: [ApiVersion("1.0")] [Route("api/v{version:apiVersion}/products")] [ApiController] public class ProductsV1Controller : ControllerBase [HttpGet] public IActionResult Get() => Ok("Version 1"); ⚠ 5. What is ProblemDetails? Follow : ProblemDetails is a standardized JSON structure for API error responses (RFC 7807). Example Output: "type": " "title": "Resource not found", "status": 404, "detail": "Product with ID 5 was not found" Usage: return NotFound(new ProblemDetails Title = "Product not found", Status = StatusCodes.Status404NotFound, Detail = "The product ID 5 does not exist." }); 🚦 6. How to return custom HTTP status codes? You can use built-in helpers from ControllerBase: Method Status Code Ok() 200 Created() / CreatedAtAction() 201 NoContent() 204 BadRequest() 400 Unauthorized() 401 Follow : NotFound() 404 StatusCode(500) Custom Example: return StatusCode(503, "Service temporarily unavailable"); 📄 7. How to implement pagination in APIs? Pagination helps manage large datasets efficiently. Example: [HttpGet] public IActionResult GetProducts([FromQuery] int page = 1, [FromQuery] int size = 10) var data = _context.Products .Skip((page - 1) * size) .Take(size) .ToList(); var totalCount = _context.Products.Count(); Response.Headers.Add("X-Total-Count", totalCount.ToString()); return Ok(data); ✅ Supports GET /api/products?page=2&size=5. 🔐 8. How to secure APIs with JWT tokens? Use JWT (JSON Web Token) authentication for stateless security. Follow : Setup in Program.cs: builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationS cheme) .AddJwtBearer(options => options.TokenValidationParameters = new TokenValidationParameters ValidateIssuer = true, ValidIssuer = " ValidateAudience = true, ValidAudience = " IssuerSigningKey = new SymmetricSecurityKey( Encoding.UTF8.GetBytes("super-secret-key")) }); Then protect controllers: [Authorize] [ApiController] [Route("api/[controller]")] public class OrdersController : ControllerBase [HttpGet] public IActionResult GetOrders() => Ok("Secure data"); ⚡ 9. What is rate limiting in .NET 8? .NET 8 introduces built-in rate limiting middleware to control API request rates. Example: builder.Services.AddRateLimiter(options => Follow : options.AddFixedWindowLimiter("fixed", opt => opt.PermitLimit = 5; // 5 requests opt.Window = TimeSpan.FromSeconds(10); // per 10 seconds opt.QueueLimit = 0; }); }); var app = builder.Build(); app.UseRateLimiter(); app.MapGet("/api/data", () => "Hello") .RequireRateLimiting("fixed"); ✅ Prevents abuse or DDoS attacks by throttling requests. 🚨 10. How do you handle exceptions in APIs? Use global exception handling middleware instead of try/catch everywhere. Example: app.UseExceptionHandler("/error"); app.Map("/error", (HttpContext context) => var exception = context.Features.Get<IExceptionHandlerFeature>()?.Error; return Results.Problem(title: "Unexpected error", detail: exception?.Message); }); Or write a custom middleware for consistent error formatting. Follow : 🧾 11. How to use Swagger / OpenAPI? Swagger generates interactive API documentation automatically. Setup: builder.Services.AddEndpointsApiExplorer(); builder.Services.AddSwaggerGen(); var app = builder.Build(); if (app.Environment.IsDevelopment()) app.UseSwagger(); app.UseSwaggerUI(); Run → Navigate to ✅ You can test endpoints directly from the browser. 🧰 12. What is NSwag or Swashbuckle? Both tools generate OpenAPI/Swagger documentation, but with slight differences: Tool Description Swashbuckle.AspNetCor Most common; adds Swagger UI, docs, and JSON schema NSwag Adds extra features like client SDK generation for C#/TypeScript Example (NSwag client generation): Follow : nswag openapi2csclient /input: /output:Client.cs 📤 13. How to upload files via Web API? Use IFormFile for file uploads. Controller Example: [HttpPost("upload")] public async Task<IActionResult> UploadFile(IFormFile file) if (file == null || file.Length == 0) return BadRequest("No file uploaded."); var path = Path.Combine("wwwroot/uploads", file.FileName); using var stream = new FileStream(path, FileMode.Create); await file.CopyToAsync(stream); return Ok(new { file.FileName, file.Length }); Client sends multipart/form-data POST requests. 🌐 14. How to implement CORS? CORS (Cross-Origin Resource Sharing) allows requests from other domains (e.g., frontend apps). Enable in Program.cs: builder.Services.AddCors(options => Follow : options.AddPolicy("AllowReactApp", policy => policy.WithOrigins(" .AllowAnyHeader() .AllowAnyMethod()); }); var app = builder.Build(); app.UseCors("AllowReactApp"); ✅ Now your React or Angular frontend can call your API safely. 🚀 15. What’s new in .NET 8 Minimal APIs? Minimal APIs let you build lightweight REST endpoints without controllers — great for microservices. Example: var builder = WebApplication.CreateBuilder(args); var app = builder.Build(); app.MapGet("/products", () => new[] { "Phone", "Tablet" }); app.MapPost("/products", (Product product) => Results.Created($"/products/{product.Id}", product)); app.Run(); New in .NET 8: Route groups for grouping endpoints Input validation with [Validate] attributes Enhanced OpenAPI (Swagger) support Rate limiting, Authorization, and Filters integration Follow : Typed results for consistent HTTP responses ✅ Minimal APIs now rival traditional controllers for small, fast APIs. Performance & Caching

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.

Short answer: ASP.NET Core configuration is flexible, layered, and environment-aware.

Explain a bit more

It reads settings from multiple sources (JSON files, environment variables, command-line rgs, etc.) and merges them into a single configuration object (IConfiguration).

Example code

In Program.cs: var builder = WebApplication.CreateBuilder(args); // Access configuration var appName = builder.Configuration["AppSettings:Name"]; SP.NET Core automatically loads:

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.

Short answer: builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationS cheme) .AddJwtBearer(options => { options.TokenValidationParameters = new TokenValidationParameters { ValidateIssuer = true, ValidateAudience = true, ValidateLifetime = true, ValidateIssuerSigningKey = true, ValidIssuer = " ValidAudience = " IssuerSigningKey = new… SymmetricSecurityKey(……… Encoding.UTF8.GetBytes("super-secret-key-123")) }; });…

Explain a bit more

builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationS cheme) .AddJwtBearer(options => { options.TokenValidationParameters = new TokenValidationParameters { ValidateIssuer = true, ValidateAudience = true, ValidateLifetime = true, ValidateIssuerSigningKey = true, ValidIssuer = " ValidAudience = " IssuerSigningKey = new SymmetricSecurityKey( Encoding.UTF8.GetBytes("super-secret-key-123")) }; }); builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationS cheme) .AddJwtBearer(options => { options.TokenValidationParameters = new TokenValidationParameters { ValidateIssuer = true, ValidateAudience = true,…

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.

Short answer: var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build();…

Explain a bit more

app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization();

Example code

var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization(); var app = builder.Build(); app.UseAuthentication(); app.UseAuthorization();

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.

Short answer: options.UseLazyLoadingProxies().UseSqlServer(...); options.UseLazyLoadingProxies().UseSqlServer(...); options.UseLazyLoadingProxies().UseSqlServer(...); options.UseLazyLoadingProxies().UseSqlServer(...);

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.

Short answer: Entity Framework Core (EF Core) is a modern, lightweight, cross-platform ORM (Object Relational Mapper) from Microsoft. It allows .NET developers to work with databases using .NET objects, without writing most SQL manually. {

Example code

public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) { } public DbSet<Product> Products { get; set; }
} 🧱 4. What are Migrations? Migrations allow you to evolve your database schema as your models change, without losing existing data. Commands: dotnet ef migrations add InitialCreate dotnet ef database update This creates a Migrations folder with code that applies schema changes automatically. 🧩 5. What is the OnModelCreating method used for? OnModelCreating is where you configure entity behavior and relationships using the Fluent API. Example: protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<Product>() .Property(p => p.Name) .HasMaxLength(100) .IsRequired(); modelBuilder.Entity<Order>() .HasMany(o => o.Items) .WithOne(i => i.Order) .HasForeignKey(i => i.OrderId);
} Use it for constraints, relationships, indexes, seeding, and more. 💤 6. How do you enable Lazy Loading in EF Core? Lazy loading means related entities are loaded automatically when accessed. To enable it: Install the package: dotnet add package Microsoft.EntityFrameworkCore.Proxies

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.

Short answer: ASP.NET Core is a cross-platform, open-source framework for building modern web applications, APIs, and microservices.

Explain a bit more

It’s a complete rewrite of the old ASP.NET framework, designed to be lightweight, modular, and cloud-ready. In ASP.NET MVC 5, you’d deploy only to IIS on Windows. In ASP.NET Core, the same app can run on a Linux server using Nginx + Kestrel — perfect for Docker or cloud environments. ⚙ 2. Explain the request-processing pipeline in ASP.NET Core. ASP.NET Core handles incoming requests through a middleware pipeline. Each middleware can process, modify, or short-circuit requests before they reach the endpoint. Flow

Example code

Request → Middleware 1 (Logging) → Middleware 2 (Authentication) → Middleware 3 (Routing) → Controller / Endpoint → Response → Back through pipeline Follow : Example: If you log requests, check authentication, and handle static files — they execute in the order you add them in Program.cs. app.UseStaticFiles(); app.UseRouting(); app.UseAuthentication(); app.UseAuthorization(); app.MapControllers(); 🧱 3. What is Kestrel? Kestrel is a cross-platform web server built into ASP.NET Core. It’s fast, lightweight, and serves as the default web server. You can run it standalone or behind a reverse proxy like IIS or Nginx. Real Example: When you run dotnet run, your app listens on — that’s Kestrel serving your app. 🖥 4. What is the role of IIS when hosting ASP.NET Core apps? IIS acts as a reverse proxy. It forwards incoming HTTP requests to the Kestrel server running your ASP.NET Core app. This setup provides: Process management (auto-restart) Port sharing (multiple sites) Windows authentication Logging and monitoring Follow : In short: IIS → forwards → Kestrel → runs the app. 🚀 5. What is the Startup class used for? The Startup class defines how your app configures services (DI, authentication, etc.) and sets up middleware (routing, static files, error pages, etc.). Example: public class Startup public void ConfigureServices(IServiceCollection services) services.AddControllers(); public void Configure(IApplicationBuilder app) app.UseRouting(); app.UseEndpoints(endpoints => endpoints.MapControllers()); 🧭 6. Explain the purpose of Program.cs in .NET 6+. In .NET 6+, Startup.cs and Program.cs merged into one minimal host configuration file. It sets up the web host, configuration, logging, and middleware pipeline. Example: var builder = WebApplication.CreateBuilder(args); builder.Services.AddControllers(); var app = builder.Build(); Follow : app.MapControllers(); app.Run(); It’s simpler, faster, and easier to read. 🔹 7. What is a Minimal API? Minimal APIs are a lightweight way to build small HTTP APIs without controllers or attributes. Perfect for microservices. Example: var app = WebApplication.Create(args); app.MapGet("/hello", () => "Hello World!"); app.Run(); This single file can run a full REST endpoint. 🧰 8. What is the WebApplicationBuilder in .NET 6/7/8? WebApplicationBuilder simplifies creating and configuring a web host. It combines: IHostBuilder WebHostBuilder Configuration Services Example: var builder = WebApplication.CreateBuilder(args); Follow : builder.Services.AddDbContext<AppDbContext>(); builder.Services.AddControllers(); Then you call builder.Build() to create the WebApplication. 🛣 9. How does routing work in ASP.NET Core MVC? Routing maps incoming URLs to controllers and actions. ASP.NET Core uses Endpoint Routing to decide which route matches a request. Example: app.MapControllerRoute( name: "default", pattern: "{controller=Home}/{action=Index}/{id?}"); If the user visits /product/details/5, it maps to: ProductController → Details(int id = 5). 🏷 10. Difference between Conventional and Attribute Routing. Type Definition Example Conventional Routing Routes defined in Program.cs or Startup.cs. {controller=Home}/{action=Ind ex}/{id?} Attribute Routing Routes defined with attributes on controller actions. [Route("api/products/{id}")] Example: [Route("api/[controller]")] Follow : public class ProductsController : ControllerBase [HttpGet("{id}")] public IActionResult Get(int id) => Ok($"Product {id}"); 🧩 11. What is Endpoint Routing? Endpoint routing separates route matching from execution. It lets middleware (like authentication) know which endpoint will be executed before it runs. Example: app.UseRouting(); app.UseAuthorization(); app.UseEndpoints(endpoints => endpoints.MapControllers()); 🔄 12. Explain the role of middleware in ASP.NET Core. Middleware are components that handle requests and responses in a pipeline. Each can: Process requests Call the next middleware Or short-circuit the pipeline Example: A logging middleware that runs before all others: app.Use(async (context, next) => Console.WriteLine("Request: " + context.Request.Path); Follow : await next(); }); 🕒 13. What is the order of middleware execution? Middleware execute in the order they’re added in Program.cs. Response flows in reverse order back up the chain. Tip: Authentication must come before Authorization. UseRouting must come before UseEndpoints. 🧩 14. How to create custom middleware? Example: public class RequestLoggingMiddleware private readonly RequestDelegate _next; public RequestLoggingMiddleware(RequestDelegate next) => _next = next; public async Task Invoke(HttpContext context) Console.WriteLine($"Request for: {context.Request.Path}"); await _next(context); Register it: app.UseMiddleware<RequestLoggingMiddleware>(); Follow : 🧱 15. What is the difference between middleware and filters? Feature Middleware Filter Scope Entire app Controller/action level Runs on Every request MVC actions only Example Authentication, logging Validation, exception filters ⚒ 16. Explain the IApplicationBuilder interface. IApplicationBuilder builds the middleware pipeline. You use it in Startup.Configure() or Program.cs to add middleware via Use, Run, and Map. 🔀 17. Difference between Use, Run, and Map in middleware. Metho Description Example Use Adds middleware that can call the next component. app.UseMiddleware<Logging>(); Run Terminates the pipeline — no next middleware. app.Run(async c => await c.Response.WriteAsync("End")); Map Branches pipeline based on request path. app.Map("/admin", a => a.Run(...)); Follow : 🏗 18. What are Hosting Models in ASP.NET Core (In-process vs Out-of-process)? Model Description Performance In-process App runs inside IIS worker process (w3wp.exe). Faster (single process) Out-of-proces IIS acts as reverse proxy to Kestrel. Slight overhead Example: For Windows servers, in-process gives best performance. For cross-platform Docker, use out-of-process. 🌍 19. Explain Web Host vs Generic Host. Host Type Used For Example Web Host Web apps (ASP.NET Core ≤ 2.2) WebHost.CreateDefaultBui lder() Generic Host Any app: web, worker, console (≥ 3.0) Host.CreateDefaultBuilde r() Generic Host unifies background tasks, APIs, and services in one model. ⚙ 20. How does configuration binding work in ASP.NET Core? ASP.NET Core can automatically bind configuration from: appsettings.json Environment variables Follow : Command-line arguments Example: // appsettings.json "AppSettings": { "SiteName": "MyShop", "Version": "1.0" // POCO public class AppSettings public string SiteName { get; set; } public string Version { get; set; } // Program.cs builder.Services.Configure<AppSettings>( builder.Configuration.GetSection("AppSettings")); You can inject IOptions<AppSettings> anywhere. MVC Architecture & Controllers

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.

Short answer: Middleware vs Filters vs Handlers Concept When It Runs Scope Example Middleware Before/after request Global Logging, authentication Filters Around controller/action Controller/action Authorization, validation Handlers Authentication/Authorization Global or endpoint JWT handler, Cookie auth 1⃣

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.

Short answer: How ASP.NET Core Handles gRPC gRPC uses HTTP/2, binary serialization (Protobuf), and strongly typed contracts. Add gRPC service: builder.Services.AddGrpc(); app.MapGrpcService<MyGrpcService>(); Clients can call server methods over HTTP/2 for high-performance RPC. Use Cases: Microservices, real-time streaming, low-latency APIs.

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.

Short answer: dotnet publish -c Release -o C:\inetpub\wwwroot\MyApp

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.

Short answer: builder.Services.AddStackExchangeRedisCache(options => { options.Configuration = "localhost:6379"; }); builder.Services.AddStackExchangeRedisCache(options => { options.Configuration = "localhost:6379"; }); builder.Services.AddStackExchangeRedisCache(options => { options.Configuration = "localhost:6379"; });… builder.Services.AddStackExchangeRedisCache(options => { options.Configuration = "localhost:6379"; });

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.

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.

Short answer: [Authorize] [ApiController] [Route("api/[controller]")] public class OrdersController : ControllerBase { [HttpGet] public IActionResult GetOrders() => Ok("Secured Orders"); } [Authorize] [ApiController] [Route("api/[controller]")] public class OrdersController : ControllerBase { [HttpGet] public IActionResult GetOrders() =>… Ok("Secured Orders"); }… [Authorize] [ApiController] [Route("api/[controller]")] public…

Explain a bit more

class OrdersController : ControllerBase { [HttpGet] public IActionResult GetOrders() => Ok("Secured Orders"); } [Authorize] [ApiController] [Route("api/[controller]")] public class OrdersController : ControllerBase { [HttpGet] public IActionResult GetOrders() =>… Ok("Secured Orders"); }

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.

Short answer: public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get;…

Explain a bit more

set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } }

Example code

public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } } public class ApplicationUser : IdentityUser { public string FullName { get; set; } }

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.

Short answer: Use compiled queries for frequently executed queries.? is a common interview topic in ASP.NET Core MVC. Give a clear definition, then one concrete example.

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.

Short answer: public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; }

Example code

public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; } public virtual Category Category { get; set; }

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.

Short answer: SignalR vs WebSockets Feature WebSockets SignalR Protocol Low-level TCP-based High-level abstraction Transpor Only WebSockets Fallbacks: WebSockets → SSE → Long Polling Usage Real-time messages Real-time hubs with automatic reconnection, grouping, scaling ✅ Use SignalR for apps needing broadcast, connection management, and fallbacks.

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.

Short answer: How to Host in Azure App Service? Answer: Azure App Service provides PaaS hosting for ASP.NET Core apps. Steps: Publish the app via Visual Studio, CLI, or GitHub Actions. dotnet publish -c Release Create App Service in Azure portal. Deploy using FTP, Git, or CI/CD pipelines. App Service automatically configures Kestrel + reverse proxy. ✅ Supports scaling, HTTPS, and monitoring out-of-the-box.

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.

Short answer: pp.MapHealthChecks("/health"); pp.MapHealthChecks("/health"); pp.MapHealthChecks("/health"); pp.MapHealthChecks("/health"); pp.MapHealthChecks("/health"); pp.MapHealthChecks("/health"); pp.MapHealthChecks("/health"); pp.MapHealthChecks("/health");

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.

Short answer: Role-based authorization restricts access based on user roles. ssign a role: wait _userManager.AddToRoleAsync(user, "Admin"); Use in controllers: [Authorize(Roles = "Admin")] public IActionResult Dashboard() => View(); You can also combine roles: [Authorize(Roles = "Admin,Manager")] 🧭 7. {

Example code

public int Age { get; }
public MinimumAgeRequirement(int age) => Age = age;
}
public class MinimumAgeHandler : uthorizationHandler<MinimumAgeRequirement> { protected override Task HandleRequirementAsync( uthorizationHandlerContext context, MinimumAgeRequirement requirement) {
var birthDateClaim = context.User.FindFirst(c => c.Type == "BirthDate"); if (birthDateClaim != null)
{
var birthDate = DateTime.Parse(birthDateClaim.Value);
if (birthDate.AddYears(requirement.Age) <= DateTime.Today) context.Succeed(requirement); }
return Task.CompletedTask;
}
} Register it: builder.Services.AddAuthorization(options => { options.AddPolicy("AdultOnly", policy => policy.Requirements.Add(new MinimumAgeRequirement(18))); }); builder.Services.AddSingleton<IAuthorizationHandler, MinimumAgeHandler>(); Use it: [Authorize(Policy = "AdultOnly")] public IActionResult BuyAlcohol() => Ok("Access granted"); 🍪 9. What is cookie authentication in ASP.NET Core? Cookie authentication stores user information in an encrypted cookie on the browser. When the user revisits, the cookie is used to identify them. Configure: builder.Services.AddAuthentication(CookieAuthenticationDefaults.Auth enticationScheme) .AddCookie(options => {
options.LoginPath = "/Account/Login";

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.

Short answer: Claims-based authentication is based on claims — pieces of information about the user (like email, role, or permissions).

Explain a bit more

Each user has a collection of claims represented as key-value pairs.

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.