Interview Q&A

Short answer: Introduced in ASP.NET Core 3.0. Centralized routing system that decouples route matching from middleware. Routes requests to endpoints defined by controllers, Razor Pages, minimal APIs. Supports route-based middleware filters.

Example code

Introduced in ASP.NET Core 3.0. Centralized routing system that decouples route matching from middleware. Routes requests to endpoints defined by controllers, Razor Pages, minimal APIs. Supports route-based middleware filters.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: pplied globally. Attribute routing: Routes declared directly on controllers/actions via attributes ([Route], [HttpGet]). Attribute routing is more flexible and explicit.

Real-world example (ShopNest)

ShopNest registers AppDbContext as Scoped and IMemoryCache as Singleton. Putting DbContext in a Singleton causes threading bugs.

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: Conventional routing: Routes defined centrally (usually in Startup), patterns applied globally. Attribute routing: Routes declared directly on controllers/actions via attributes ([Route], [HttpGet]). Attribute routing is more flexible and explicit.

Real-world example (ShopNest)

ShopNest registers AppDbContext as Scoped and IMemoryCache as Singleton. Putting DbContext in a Singleton causes threading bugs.

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: Add Swashbuckle.AspNetCore NuGet package. Configure Swagger services (builder.Services.AddSwaggerGen()). Enable middleware (app.UseSwagger(), app.UseSwaggerUI()). Customize with options like API info, document filters, UI themes.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: types Automatically selects response format (JSON, XML) based on Accept header. Configured via formatters in MVC options. Falls back to default formatter if no match.

Real-world example (ShopNest)

ShopNest registers AppDbContext as Scoped and IMemoryCache as Singleton. Putting DbContext in a Singleton causes threading bugs.

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: Standardized error response format defined by RFC 7807. Contains properties like status, title, detail, instance. Used by default in ASP.NET Core for error responses.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: error responses Implement custom exception handling middleware. Catch exceptions, set HTTP status, and return custom JSON payload. Use UseExceptionHandler() or global filters. Customize ProblemDetails or your own error models.

Real-world example (ShopNest)

ShopNest pipeline order matters: exception handling → HTTPS → auth → authorization → endpoints. Auth must run before protected 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: Accept CancellationToken parameter in action methods. Pass token to async calls to support request cancellation. Improves responsiveness and resource management.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: configure them Default max request body size is 30 MB. Configure via RequestSizeLimit attribute or KestrelServerOptions.Limits.MaxRequestBodySize. For IIS, adjust maxAllowedContentLength.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: Add ResponseCompression middleware. Register compression providers (AddResponseCompression()) in Program.cs. Configure supported MIME types and compression level.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: System.Text.Json: Default in .NET Core 3+, fast, built-in, less feature-rich. Newtonsoft.Json: More mature, supports advanced scenarios (e.g., polymorphic deserialization). Can switch to Newtonsoft by adding AddNewtonsoftJson() in MVC options.

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.