{"department":null,"description":null,"descriptionStatus":null,"descriptionUpdatedAt":null,"id":"31dce4e1-d8b9-4896-bce7-83c979c20405","label":"ASP.NET Core","shortDescription":null,"slug":"asp-net-core","updatedAt":"2026-02-17T09:10:53.552Z","quizzes":[{"difficulty":"beginner","id":"b7f23g-3UH","questionCount":15,"questions":[{"index":0,"options":["Index.cshtml","Program.cs","Web.config","Startup.cs"],"question":"What file serves as the entry point for an ASP.NET Core application?","difficulty":"beginner","explanation":"Program.cs is the entry point of an ASP.NET Core application where the web host is created and configured.","correctIndex":1},{"index":1,"options":["To store controller classes","To store configuration files","To store static files like CSS, JavaScript, and images","To store database migration files"],"question":"What is the purpose of the wwwroot folder in an ASP.NET Core project?","difficulty":"beginner","explanation":"The wwwroot folder is the web root of the application and contains static files that are served directly to clients.","correctIndex":2},{"index":2,"options":["Model-Variable-Controller","Model-View-Controller","Method-View-Code","Module-View-Component"],"question":"What does MVC stand for in ASP.NET Core MVC?","difficulty":"beginner","explanation":"MVC stands for Model-View-Controller, a design pattern that separates an application into three main components.","correctIndex":1},{"index":3,"options":["[HttpGet]","[AcceptGet]","[GetRequest]","[RouteGet]"],"question":"Which attribute is used to specify that a controller action should respond to HTTP GET requests?","difficulty":"beginner","explanation":"The [HttpGet] attribute is used to restrict a controller action to only handle HTTP GET requests.","correctIndex":0},{"index":4,"options":["A technique for client-side routing","A way to inject HTML into views","A design pattern where dependencies are provided to a class rather than created within it","A method for database operations"],"question":"What is Dependency Injection in ASP.NET Core?","difficulty":"beginner","explanation":"Dependency Injection is a design pattern where services are provided to classes that need them, promoting loose coupling and testability.","correctIndex":2},{"index":5,"options":["web.config","config.ini","appsettings.json","settings.xml"],"question":"Which file is typically used to store application configuration settings in ASP.NET Core?","difficulty":"beginner","explanation":"appsettings.json is the standard JSON-based configuration file used in ASP.NET Core applications to store settings.","correctIndex":2},{"index":6,"options":["To authorize database connections","To enable CORS for an endpoint","To validate model properties","To restrict access to a controller or action to authenticated users"],"question":"What is the purpose of the [Authorize] attribute in ASP.NET Core?","difficulty":"beginner","explanation":"The [Authorize] attribute restricts access to a controller or action method to only those users who have been authenticated.","correctIndex":3},{"index":7,"options":["A JavaScript framework","A markup syntax for embedding server-based code into webpages","A database query language","A CSS preprocessor"],"question":"What is Razor in ASP.NET Core?","difficulty":"beginner","explanation":"Razor is a server-side markup syntax that allows you to embed C# code directly into HTML views.","correctIndex":1},{"index":8,"options":["To minify JavaScript files","To create static HTML pages","To compile CSS files","To enable serving static files from the wwwroot folder"],"question":"What is the purpose of app.UseStaticFiles() in ASP.NET Core?","difficulty":"beginner","explanation":"app.UseStaticFiles() is middleware that enables the application to serve static files such as CSS, JavaScript, and images from the wwwroot folder.","correctIndex":3},{"index":9,"options":["A database helper class","Server-side code that renders HTML elements in Razor files","A CSS utility framework","A client-side JavaScript library"],"question":"What is a Tag Helper in ASP.NET Core?","difficulty":"beginner","explanation":"Tag Helpers are server-side components that enable server-side rendering of HTML elements in Razor files, providing an HTML-friendly development experience.","correctIndex":1},{"index":10,"options":["A JSON object","An HTML string","A database record","A flexible return type that can represent various HTTP responses"],"question":"What does the IActionResult return type represent in a controller action?","difficulty":"beginner","explanation":"IActionResult is an interface that allows a controller action to return different types of results like views, JSON, status codes, or redirects.","correctIndex":3},{"index":11,"options":["IConfiguration","ConfigurationManager","AppSettingsReader","WebConfiguration"],"question":"Which interface is used to read configuration values in ASP.NET Core?","difficulty":"beginner","explanation":"IConfiguration is the primary interface used in ASP.NET Core to read configuration values from various sources like appsettings.json and environment variables.","correctIndex":0},{"index":12,"options":["A UI component library","Software components that form a pipeline to handle requests and responses","A database connection tool","A testing framework"],"question":"What is middleware in ASP.NET Core?","difficulty":"beginner","explanation":"Middleware are software components assembled in a pipeline that handle requests and responses in an ASP.NET Core application.","correctIndex":1},{"index":13,"options":["[Endpoint]","[Path]","[Route]","[Url]"],"question":"Which attribute is used to specify a route template on a controller action?","difficulty":"beginner","explanation":"The [Route] attribute is used to define URL patterns that map to controller actions in ASP.NET Core routing.","correctIndex":2},{"index":14,"options":["The process of linking CSS to HTML elements","The process of binding a database to a model class","The process of mapping HTTP request data to action method parameters","The process of connecting views to controllers"],"question":"What is model binding in ASP.NET Core?","difficulty":"beginner","explanation":"Model binding automatically maps data from HTTP requests (form values, route data, query strings) to action method parameters and properties.","correctIndex":2}]},{"difficulty":"advanced","id":"ohxuquc5wE","questionCount":16,"questions":[{"index":0,"options":["The DI container automatically replaces the scoped registration with a transient one","The scoped service behaves as a singleton, sharing the same instance across all requests","The scoped service is re-resolved from a new scope for each method call","An InvalidOperationException is thrown at runtime when the scoped service is first accessed"],"question":"When a scoped service is inadvertently injected into a singleton service in ASP.NET Core, what is the runtime behavior when scope validation is disabled?","difficulty":"advanced","explanation":"When scope validation is disabled (the default in Production), the scoped service is resolved from the root container and becomes a 'captive dependency' that behaves as a singleton, sharing state across all requests and potentially causing data corruption.","correctIndex":1},{"index":1,"options":["The next middleware runs in parallel with the remaining code in the current middleware","The next middleware and all downstream middleware execute, then control returns to the current middleware after the await","The next middleware executes synchronously, blocking the current thread until the entire pipeline completes","The next middleware runs on a separate thread, and the current middleware continues immediately"],"question":"In the ASP.NET Core middleware pipeline, when a middleware component calls `await next(context)`, what is the execution behavior?","difficulty":"advanced","explanation":"The middleware pipeline forms a request delegate chain. When next(context) is called, the request flows through all downstream middleware, then execution unwinds back through each middleware in reverse order, allowing code after await next(context) to execute.","correctIndex":1},{"index":2,"options":["At application startup, before the host begins accepting requests","On each request that accesses IOptions or IOptionsMonitor","When the Configure method for the options is first called","When the options are first injected into any service via constructor injection"],"question":"When using `services.AddOptions().ValidateOnStart()` in ASP.NET Core, when does the validation logic execute?","difficulty":"advanced","explanation":"ValidateOnStart() causes validation to run during host startup (specifically when IHostedService.StartAsync is invoked), ensuring invalid configuration fails fast before the application accepts any requests.","correctIndex":0},{"index":3,"options":["The hosted service is marked as unhealthy, but other services continue starting","The exception is logged, and the application continues running without that hosted service","The exception is caught and the StartAsync method is retried up to three times","The application startup fails, and the host shuts down"],"question":"When an IHostedService throws an unhandled exception during StartAsync, what is the default behavior in ASP.NET Core?","difficulty":"advanced","explanation":"If an IHostedService throws during StartAsync, the host fails to start entirely and the application shuts down. This fail-fast behavior prevents the application from running in an inconsistent state.","correctIndex":3},{"index":4,"options":["It is registered by default; this is a common misconception","It is only needed for WebSockets and Server-Sent Events, which are not commonly used","It has significant performance overhead due to AsyncLocal storage, and it encourages accessing HttpContext outside the request pipeline","It causes thread starvation in high-traffic applications"],"question":"Why is IHttpContextAccessor not registered in ASP.NET Core's DI container by default?","difficulty":"advanced","explanation":"IHttpContextAccessor uses AsyncLocal which has performance implications, and its availability encourages the anti-pattern of accessing HttpContext outside the request pipeline, such as in services that should be context-free.","correctIndex":2},{"index":5,"options":["It reduces memory allocation by caching route matches in a static dictionary","It eliminates the need for attribute routing on controllers","It automatically generates OpenAPI documentation from route templates","Routing metadata is available early in the middleware pipeline, allowing authorization and CORS to be evaluated before the endpoint executes"],"question":"What is a key architectural advantage of endpoint routing over the legacy routing system in ASP.NET Core?","difficulty":"advanced","explanation":"Endpoint routing decouples routing decisions from middleware execution, making route metadata available early. This allows authorization policies, CORS, and other concerns to be evaluated before the endpoint handler is invoked, improving security and reducing unnecessary work.","correctIndex":3},{"index":6,"options":["To improve service resolution performance by using dictionary-based lookup instead of linear search","To register and resolve multiple implementations of the same interface using distinct keys","To automatically configure named options instances based on service keys","To enable scoped services to be safely injected into singleton services via keyed resolution"],"question":"In .NET 8's dependency injection, what is the primary purpose of keyed services?","difficulty":"advanced","explanation":"Keyed services allow registering multiple implementations of the same interface under different keys, and then resolving a specific implementation using the [FromKeyedServices] attribute or IKeyedServiceProvider, solving the problem of choosing between multiple implementations.","correctIndex":1},{"index":7,"options":["Response Caching works only with authenticated users; Output Caching works only with anonymous users","Response Caching stores data in memory; Output Caching stores data in a distributed cache","Response Caching respects HTTP cache headers and can produce 304 Not Modified responses; Output Caching is server-side only and ignores client cache headers","Response Caching is only available for minimal APIs; Output Caching is only for MVC controllers"],"question":"What is a fundamental difference between Response Caching middleware and Output Caching middleware in ASP.NET Core?","difficulty":"advanced","explanation":"Response Caching middleware implements HTTP caching semantics, respecting Cache-Control headers and producing 304 responses. Output Caching is a server-side caching mechanism that caches responses based on configurable policies, independent of HTTP caching headers.","correctIndex":2},{"index":8,"options":["Inject the scoped service directly into the middleware constructor","Use IServiceProvider.GetRequiredService in the middleware constructor","Register the middleware as a scoped service in the DI container","Resolve the scoped service from HttpContext.RequestServices within InvokeAsync"],"question":"In ASP.NET Core, how should a convention-based middleware access scoped services safely?","difficulty":"advanced","explanation":"Convention-based middleware is instantiated once at application startup as a singleton. To access scoped services correctly, resolve them from HttpContext.RequestServices within InvokeAsync, which ensures they are scoped to the current HTTP request.","correctIndex":3},{"index":9,"options":["The overall status requires a custom policy to be configured; otherwise, it defaults to 'Healthy'","The overall status is determined by the last registered health check's result","The overall status is determined by the worst individual status returned, where Unhealthy is worse than Degraded, which is worse than Healthy","The overall status is always 'Unhealthy' if any individual check fails"],"question":"When multiple health checks are registered in ASP.NET Core, how is the overall health status determined?","difficulty":"advanced","explanation":"The overall health status is determined by the worst individual status. If any check returns Unhealthy, the overall status is Unhealthy. If none are Unhealthy but any is Degraded, the overall status is Degraded. Otherwise, it's Healthy.","correctIndex":2},{"index":10,"options":["Automatic HTTP 400 responses for invalid model state","Inference of [FromRoute] for parameters matching route template parameters","Inference of [FromBody] for complex type parameters","Automatic ProblemDetails responses for unhandled exceptions in controller actions"],"question":"When the [ApiController] attribute is applied to a controller in ASP.NET Core, which behavior is NOT automatically enabled?","difficulty":"advanced","explanation":"The [ApiController] attribute enables automatic 400 responses for model validation, parameter source inference, and attribute routing requirements, but does NOT automatically convert unhandled exceptions to ProblemDetails responses. That requires additional configuration like exception handling middleware.","correctIndex":3},{"index":11,"options":["To configure rate limiting policies for specific endpoints","To provide endpoint-specific cross-cutting concerns, allowing code to run before and after route handlers similar to action filters in controllers","To replace the need for middleware in handling cross-cutting concerns across the entire application","To validate route parameters and apply constraints before the endpoint handler executes"],"question":"In ASP.NET Core minimal APIs, what is the primary role of endpoint filters?","difficulty":"advanced","explanation":"Endpoint filters in minimal APIs provide a way to execute code before and after route handlers, similar to action filters in MVC controllers. They are endpoint-specific and complement (rather than replace) middleware for cross-cutting concerns like validation, logging, and authorization.","correctIndex":1},{"index":12,"options":["The request is rejected with HTTP 413 Payload Too Large before reaching the application layer","The request body is automatically buffered to disk to avoid memory pressure","An InvalidOperationException is thrown during model binding in the controller","The request body is truncated, and processing continues with partial data"],"question":"In ASP.NET Core, what happens when an incoming request body exceeds the Kestrel server's MaxRequestBodySize limit?","difficulty":"advanced","explanation":"When the request body exceeds Kestrel's MaxRequestBodySize limit, Kestrel rejects the request with HTTP 413 (Payload Too Large) at the transport layer, before the request reaches the application middleware pipeline.","correctIndex":0},{"index":13,"options":["They must implement IDisposable.Dispose to handle graceful shutdown","StopAsync is called on each service, and the host waits up to the configured ShutdownTimeout for them to complete","They are immediately terminated regardless of ongoing work","They continue running until all in-flight HTTP requests complete, then shut down"],"question":"When an ASP.NET Core application receives a shutdown signal, what happens to registered IHostedService instances?","difficulty":"advanced","explanation":"When the application shuts down, StopAsync is called on each IHostedService in reverse registration order. The host waits for all StopAsync calls to complete within the configured ShutdownTimeout (default 30 seconds). If the timeout expires, the host forces shutdown.","correctIndex":1},{"index":14,"options":["Use lock statements around all read and write operations on the list","Register the service as scoped instead of singleton to avoid concurrent access","Create a new list on updates and use Interlocked.Exchange to atomically swap the reference, allowing lock-free reads","Replace List with ConcurrentBag for thread-safe access"],"question":"A singleton service in ASP.NET Core maintains a frequently-read, rarely-updated cache using a List. What is the most thread-safe and performant approach for updates?","difficulty":"advanced","explanation":"For a read-heavy, write-rarely scenario, creating a new list on updates and using Interlocked.Exchange to atomically swap the reference allows lock-free reads. This provides optimal read performance while ensuring thread safety, as readers always see a consistent snapshot.","correctIndex":2},{"index":15,"options":["To limit the time a client has to send the complete request body headers","To configure the maximum idle time for client connections before they are closed","To configure the timeout for database connections used during request processing","To set the maximum duration for request processing per endpoint, aborting long-running requests via CancellationToken"],"question":"In ASP.NET Core, what is the purpose of the Request Timeout middleware (added in .NET 8)?","difficulty":"advanced","explanation":"The Request Timeout middleware allows configuring per-endpoint timeout policies that can abort long-running requests. It uses CancellationToken to signal timeout, allowing endpoints to cooperatively cancel work when the configured duration is exceeded.","correctIndex":3}]},{"difficulty":"intermediate","id":"pFJuNdkP0O","questionCount":15,"questions":[{"index":0,"options":["PerRequest","Singleton","Transient","Scoped"],"question":"In ASP.NET Core dependency injection, which service lifetime ensures that a new instance is created for each HTTP request but shared within that request?","difficulty":"intermediate","explanation":"Scoped services are created once per HTTP request and shared within that request scope, making them ideal for per-request data like database contexts.","correctIndex":3},{"index":1,"options":["Authentication is faster and should run first for performance","The authorization middleware depends on the authentication middleware populating the ClaimsPrincipal","UseAuthorization() will throw an exception if called first","They must be called in alphabetical order by convention"],"question":"When configuring middleware in ASP.NET Core, why must UseAuthentication() be called before UseAuthorization()?","difficulty":"intermediate","explanation":"UseAuthentication populates the User property on HttpContext with a ClaimsPrincipal, which UseAuthorization then uses to make authorization decisions.","correctIndex":1},{"index":2,"options":["IOptions","IOptionsMonitor","IOptionsSnapshot","IOptionsChangeToken"],"question":"Which interface in ASP.NET Core allows you to receive notifications when configuration options are reloaded at runtime?","difficulty":"intermediate","explanation":"IOptionsMonitor supports scenario-based reloading of configuration and provides change notifications, whereas IOptionsSnapshot is scoped per request.","correctIndex":1},{"index":3,"options":["[Authorize(Roles = \"AdminOnly\")]","[Authorize(Policy = \"AdminOnly\")]","[Policy(\"AdminOnly\")]","[Authorize(Permission = \"AdminOnly\")]"],"question":"How do you apply a custom authorization policy named \"AdminOnly\" to a specific API controller action?","difficulty":"intermediate","explanation":"The Authorize attribute's Policy property is used to apply a named authorization policy that was registered in the authorization options during startup configuration.","correctIndex":1},{"index":4,"options":["UseDeveloperExceptionPage()","UseExceptionHandler()","UseErrorHandling()","UseStatusCodePages()"],"question":"Which middleware should be registered early in the pipeline to catch exceptions from subsequent middleware and return appropriate error responses in production?","difficulty":"intermediate","explanation":"UseExceptionHandler() catches exceptions, logs them, and re-executes the request in an alternate pipeline, making it suitable for production error handling.","correctIndex":1},{"index":5,"options":["next()","context.HttpContext.ExecuteAction()","context.ExecuteActionAsync()","context.Next()"],"question":"When implementing IAsyncActionFilter, what must you invoke on the ActionExecutionDelegate parameter to allow the action method and subsequent filters to execute?","difficulty":"intermediate","explanation":"The IAsyncActionFilter interface receives an ActionExecutionDelegate named 'next' that must be invoked to execute the action method and subsequent action filters in the pipeline.","correctIndex":0},{"index":6,"options":["It restricts the route to only match when the id segment can be parsed as an integer","It ensures the id parameter is required in the URL","It converts the id parameter to an integer automatically","It validates that id is an integer after model binding"],"question":"What is the purpose of the `{id:int}` route constraint in an attribute route like [HttpGet(\"{id:int}\")]?","difficulty":"intermediate","explanation":"Route constraints restrict which URLs match a route template. The :int constraint ensures the route only matches when the id segment is a valid integer, preventing non-integer values from reaching the action.","correctIndex":0},{"index":7,"options":["services.Bind(Configuration)","services.Configure(Configuration)","services.AddOptions(Configuration)","services.Register(Configuration)"],"question":"Which method is used to bind a configuration section to a strongly-typed POCO class during service configuration in ASP.NET Core?","difficulty":"intermediate","explanation":"services.Configure() binds configuration values to a POCO class and registers it with the DI container so it can be injected via IOptions, IOptionsMonitor, or IOptionsSnapshot.","correctIndex":1},{"index":8,"options":["IHttpClientFactory provides automatic request/response logging","IHttpClientFactory adds built-in retry policies without additional configuration","IHttpClientFactory makes HttpClient thread-safe for concurrent use","IHttpClientFactory manages handler lifetimes to prevent socket exhaustion and DNS staleness"],"question":"What is the primary benefit of using IHttpClientFactory over directly instantiating HttpClient in ASP.NET Core?","difficulty":"intermediate","explanation":"IHttpClientFactory manages HttpMessageHandler lifetimes, pooling and recycling them to prevent socket exhaustion that occurs when HttpClient instances are disposed too frequently, and to handle DNS changes for long-lived handlers.","correctIndex":3},{"index":9,"options":["services.AddHealthCheck()","services.ConfigureHealthChecks(options => options.AddCheck())","services.AddHealthChecks().AddCheck(\"my-check\")","services.RegisterHealthCheck(\"my-check\")"],"question":"How do you register a custom health check implementation named \"my-check\" in ASP.NET Core?","difficulty":"intermediate","explanation":"AddHealthChecks() returns an IHealthChecksBuilder, and AddCheck() registers a health check implementation with an optional name and failure status.","correctIndex":2},{"index":10,"options":["All origins are pre-approved without preflight requests","Any origin can make requests including credentials","Any origin can make requests, but credentials are not allowed","CORS is completely disabled for all endpoints"],"question":"When configuring CORS in ASP.NET Core, what limitation applies if you set AllowAnyOrigin() in your CORS policy?","difficulty":"intermediate","explanation":"Setting AllowAnyOrigin permits requests from any origin, but browsers will not allow credentials (cookies, authorization headers) with wildcard origins per the CORS specification.","correctIndex":2},{"index":11,"options":["[FromRoute(\"X-Correlation-Id\")]","[FromHeader(\"X-Correlation-Id\")]","[Header(\"X-Correlation-Id\")]","[BindHeader(\"X-Correlation-Id\")]"],"question":"Which attribute should you use on an action parameter to bind its value from the request header \"X-Correlation-Id\"?","difficulty":"intermediate","explanation":"The [FromHeader] attribute explicitly tells the model binder to retrieve the parameter value from the specified HTTP request header.","correctIndex":1},{"index":12,"options":["StartAsync(CancellationToken)","Start()","RunAsync(CancellationToken)","InitializeAsync(CancellationToken)"],"question":"When implementing IHostedService for a background task, which method is called when the application host is ready to start the service?","difficulty":"intermediate","explanation":"IHostedService defines StartAsync(CancellationToken) which is called when the application host starts, and StopAsync(CancellationToken) which is called on graceful shutdown.","correctIndex":0},{"index":13,"options":["[ResponseCache(Duration = 60)]","[OutputCache(Duration = 60)]","[CacheOutput]","[CacheControl(MaxAge = 60)]"],"question":"Which attribute must be applied to an API controller action to enable server-side response caching with the ResponseCache middleware?","difficulty":"intermediate","explanation":"The ResponseCache attribute sets the appropriate cache headers and, when used with the response caching middleware, enables server-side caching for the specified duration.","correctIndex":0},{"index":14,"options":["UseRouting() is for MVC, while UseEndpoints() is for minimal APIs","UseRouting() registers routes, while UseEndpoints() defines route handlers","UseRouting() selects an endpoint, while UseEndpoints() executes the selected endpoint","UseRouting() handles URL generation, while UseEndpoints() handles URL matching"],"question":"What is the key difference between UseRouting() and UseEndpoints() in ASP.NET Core's endpoint routing?","difficulty":"intermediate","explanation":"UseRouting() performs route matching and sets the selected endpoint on the HttpContext, while UseEndpoints() executes the endpoint that was selected by UseRouting(), enabling middleware to run between these two steps.","correctIndex":2}]}]}

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