DotNet Coding Specialist (DCS) — ASP.NET Core — Questions and Answers

Question 1: Which service lifetime registers a new instance for every HTTP request in ASP.NET Core?

Singleton
PerRequest
Transient
Scoped (Correct answer)

Correct answer: Scoped

Scoped services are created once per HTTP request and shared within that request's scope.

Question 2: What does the Logging:LogLevel:Default configuration key control?

The default log provider to use
The minimum log level for all categories that don't have a specific override (Correct answer)
The maximum number of log entries stored
The output format of log messages

Correct answer: The minimum log level for all categories that don't have a specific override

Logging:LogLevel:Default sets the baseline minimum severity; categories with specific entries override this default.

Question 3: Which CLI command initializes User Secrets for an ASP.NET Core project?

dotnet user-secrets init (Correct answer)
dotnet init secrets
dotnet secret init
dotnet secrets create

Correct answer: dotnet user-secrets init

dotnet user-secrets init adds a UserSecretsId GUID to the project file and sets up the local secrets store.

Question 4: Which file is the primary configuration source in an ASP.NET Core application?

settings.json
config.json
appsettings.json (Correct answer)
web.config

Correct answer: appsettings.json

appsettings.json is the default configuration file read by the ASP.NET Core host, with environment-specific overrides supported.

Question 5: What does the ASPNETCORE_ENVIRONMENT environment variable control?

The base URL of the application
The log output destination
The active environment name, affecting which appsettings and middleware are loaded (Correct answer)
The port the Kestrel server listens on

Correct answer: The active environment name, affecting which appsettings and middleware are loaded

ASPNETCORE_ENVIRONMENT sets IWebHostEnvironment.EnvironmentName, switching between Development, Staging, and Production behaviors.

Question 6: What is the purpose of the ConfigureAppConfiguration method in the host builder?

Sets the application's startup class
Configures the application's DI container
Configures logging providers
Adds or customizes configuration sources for the application (Correct answer)

Correct answer: Adds or customizes configuration sources for the application

ConfigureAppConfiguration allows adding or modifying configuration providers such as JSON files, environment variables, or custom sources.

Question 7: Which EF Core method applies pending migrations to the database?

dotnet ef database update (Correct answer)
dotnet ef schema update
dotnet ef migrations apply
dotnet ef db migrate

Correct answer: dotnet ef database update

dotnet ef database update applies all pending migrations, creating or altering tables as defined in the migration files.

Question 8: In what order does ASP.NET Core execute middleware components?

Alphabetically by class name
In the order they are registered (Correct answer)
Based on priority attribute
In reverse order of registration

Correct answer: In the order they are registered

Middleware executes in the order it is registered in the Configure method or Program.cs.

Question 9: How do you inject multiple implementations of the same interface in ASP.NET Core DI?

Inject IEnumerable<TService> in the constructor (Correct answer)
Multiple implementations are not supported
Use a factory method only
Register them under different names

Correct answer: Inject IEnumerable<TService> in the constructor

ASP.NET Core DI resolves all registered implementations of an interface when IEnumerable<TService> is injected.

Question 10: Which of the following is the ASP.NET Core application's entry point?

Application_start method of Global.asax
Configure method of Startup class
ConfigureService method of Startup class
Main method of the Program class (Correct answer)

Correct answer: Main method of the Program class

Explanation: <br> The application's main() method is used to start it up. When we run an ASP.NET Core Web application, the first thing it does is seek for the Main() function, which is where the execution begins. ASP.NET Core is then configured and started using the Main() function. The app is now an ASP.NET Core web app.

Question 11: What method is called to add MVC controllers with views in ASP.NET Core?

services.AddViewControllers()
services.AddControllersWithViews() (Correct answer)
services.AddMvc()
services.AddControllers()

Correct answer: services.AddControllersWithViews()

AddControllersWithViews() registers controllers plus Razor view support, whereas AddControllers() registers controllers for APIs only.

Question 12: By default, an ASP.NET Core web application utilizes _____as an internal web server.

Kestrel (Correct answer)
IIS
Apache
nginx

Correct answer: Kestrel

Explanation: <br> Kestrel is a cross-platform web server that supports ASP.NET Core. It's compatible with all.NET Core platforms and versions. In ASP.NET Core, it comes preinstalled as an internal server. Kestrel can be used as an edge server, which is an Internet-facing web server that can process client HTTP requests directly. The program is hosted by the dotnet.exe process in Kestrel.

Question 13: What is a short-circuiting middleware?

Middleware that runs asynchronously
Middleware that throws an exception
Middleware that does not call next(), ending the pipeline (Correct answer)
Middleware that calls next() twice

Correct answer: Middleware that does not call next(), ending the pipeline

A short-circuiting middleware returns a response without calling next(), preventing further middleware from executing.

Question 14: What is the purpose of app.Run() in the middleware pipeline?

Adds a terminal middleware that never calls next() (Correct answer)
Registers background services
Starts the web host
Runs the application

Correct answer: Adds a terminal middleware that never calls next()

app.Run() adds a terminal middleware delegate that handles requests without forwarding to any subsequent middleware.

Question 15: Which attribute defines a route template directly on an ASP.NET Core controller action?

[Path]
[HttpGet]
[Endpoint]
[Route] (Correct answer)

Correct answer: [Route]

[Route("path")] sets the route template for a controller or action, and can be combined with HTTP method attributes.

Question 16: Which mechanisms can pass data from a Razor Pages PageModel to its view beyond the strongly-typed Model property?

ViewBag only
ViewData only
ViewData, ViewBag, and TempData are all valid options (Correct answer)
TempData only

Correct answer: ViewData, ViewBag, and TempData are all valid options

ViewData (dictionary), ViewBag (dynamic wrapper over ViewData), and TempData all provide ways to pass data from a PageModel to its view.

Question 17: What method is used to add middleware to the ASP.NET Core request pipeline?

app.MapMiddleware()
app.RegisterMiddleware()
app.AddMiddleware()
app.UseMiddleware() (Correct answer)

Correct answer: app.UseMiddleware()

app.UseMiddleware<T>() is the standard method to add custom middleware to the ASP.NET Core pipeline.

Question 18: What is the purpose of the 'next' delegate in ASP.NET Core middleware?

To log the request
To return a response immediately
To call the next middleware in the pipeline (Correct answer)
To authenticate the user

Correct answer: To call the next middleware in the pipeline

Calling next(context) passes control to the subsequent middleware component in the pipeline.

Question 19: Which file is conventionally used to set a default layout for all Razor views in a folder and its subfolders?

_Layout.cshtml
_ViewImports.cshtml
_ViewStart.cshtml (Correct answer)
_Default.cshtml

Correct answer: _ViewStart.cshtml

_ViewStart.cshtml executes before any view in the same folder and is typically used to set the Layout property globally.

Question 20: In which environment is UseDeveloperExceptionPage() typically called?

Development (Correct answer)
Staging
All environments
Production

Correct answer: Development

UseDeveloperExceptionPage() shows detailed error info and should only be used in Development to avoid leaking sensitive data.

Question 21: What happens when middleware adds to HttpContext.Items?

Data is saved to session
Data is shared across all users
Data persists across requests
Data is shared only for the lifetime of the current request (Correct answer)

Correct answer: Data is shared only for the lifetime of the current request

HttpContext.Items is a dictionary scoped to the current request, allowing middleware and handlers to share data within a single request.

Question 22: What interface is used to access the DI service container manually in ASP.NET Core?

IServiceContainer
IDependencyResolver
IServiceLocator
IServiceProvider (Correct answer)

Correct answer: IServiceProvider

IServiceProvider exposes the GetService and GetRequiredService methods to resolve dependencies from the container.

Question 23: Which middleware must be added before UseAuthorization() for authentication to work?

UseJwt()
UseLogin()
UseIdentity()
UseAuthentication() (Correct answer)

Correct answer: UseAuthentication()

UseAuthentication() must precede UseAuthorization() so that user identity is established before authorization policies are evaluated.

Question 24: What happens when you call builder.Configuration.AddJsonFile("custom.json", optional: false, reloadOnChange: true)?

Only loads if the file exists, ignores missing files
Replaces all existing configuration
Loads the file once and never reloads
Throws if the file doesn't exist and watches for file changes to reload config (Correct answer)

Correct answer: Throws if the file doesn't exist and watches for file changes to reload config

optional: false throws an exception if the file is missing, and reloadOnChange: true watches the file for changes and reloads configuration automatically.

Question 25: What is constructor injection in ASP.NET Core DI?

Manually creating service instances in constructors
Declaring dependencies as constructor parameters that the DI container resolves automatically (Correct answer)
Using [Inject] attributes on constructors
Injecting configuration into constructors only

Correct answer: Declaring dependencies as constructor parameters that the DI container resolves automatically

Constructor injection is the primary DI pattern where ASP.NET Core resolves and passes dependencies automatically when creating the class.

Question 26: What is the purpose of IConfiguration.GetConnectionString("name") in ASP.NET Core?

It creates a database connection
It reads connection strings from environment variables only
It validates the connection string format
It retrieves the connection string from the ConnectionStrings section by name (Correct answer)

Correct answer: It retrieves the connection string from the ConnectionStrings section by name

GetConnectionString() is a shorthand for configuration.GetSection("ConnectionStrings")[name], a conventional location for connection strings.

Question 27: What does [Authorize(Policy = "MinimumAge")] require in ASP.NET Core?

An age filter attribute
A role named MinimumAge in the database
A MinimumAge claim in the user's JWT token
A named policy 'MinimumAge' to be registered with requirements in AddAuthorization() (Correct answer)

Correct answer: A named policy 'MinimumAge' to be registered with requirements in AddAuthorization()

Policy-based authorization evaluates the named policy's requirements, which must be registered during application startup.

Question 28: What does UseHsts() middleware do?

Compresses responses
Forces HTTPS redirects
Adds HTTP Strict Transport Security headers (Correct answer)
Enables HTTP/2

Correct answer: Adds HTTP Strict Transport Security headers

UseHsts() adds the Strict-Transport-Security response header, instructing browsers to only connect via HTTPS.

Question 29: Which of the following can be targeted by ASP.NET Core applications?

.NET Standard
.NET Framework 4x
.NET Core
All of the above (Correct answer)

Correct answer: All of the above

Explanation: <br> Frameworks that target ASP.NET Core. Only.NET Core can be targeted by ASP.NET Core 3.x and later. ASP.NET Core is primarily made up of.NET Standard libraries. Any.NET platform that implements.NET Standard 2.0 can run libraries written with.NET Standard 2.0.

Question 30: Which EF Core loading strategy fetches related entities in the same query using a JOIN?

Deferred loading
Eager loading with Include() (Correct answer)
Lazy loading
Explicit loading with Load()

Correct answer: Eager loading with Include()

Eager loading via Include() fetches related entities in a single SQL query using JOINs, avoiding the N+1 query problem.

Question 31: What route token represents an action name in a conventional route template?

[action]
<action>
{action} (Correct answer)
$(action)

Correct answer: {action}

{action} is the conventional route token that maps to the action method name in the default MVC route template.

Question 32: Which handler class must be extended to implement a custom authorization requirement handler?

RequirementHandler<T>
AuthorizationHandler<TRequirement> (Correct answer)
ClaimsAuthorizationHandler
PolicyHandler<TRequirement>

Correct answer: AuthorizationHandler<TRequirement>

Custom handlers inherit from AuthorizationHandler<TRequirement> and implement HandleRequirementAsync() to evaluate the requirement.

Question 33: What is the role of the IApplicationBuilder interface in ASP.NET Core?

It registers services in the DI container
It manages database connections
It defines application settings
It configures the request processing pipeline (Correct answer)

Correct answer: It configures the request processing pipeline

IApplicationBuilder provides methods like Use, Run, and Map to compose the middleware pipeline.

Question 34: What attribute enables property injection in ASP.NET Core Razor Pages?

[FromServices] (Correct answer)
[AutoInject]
[Inject]
[BindProperty]

Correct answer: [FromServices]

[FromServices] on a parameter or property tells the framework to resolve the value from the DI container rather than from the request.

Question 35: The ASP.NET core web application's host is set up in the________ file.

None of the these
Startup.cs
Program.cs (Correct answer)
Middleware

Correct answer: Program.cs

Explanation: <br> The application begins at Program.cs. The Program.cs file will behave similarly to the Program.cs file in a traditional.NET Framework console application. The Program.cs file is the application's entry point, and it will be responsible for registering Startup.cs, IISIntegration, and the Main method's Create a host using an instance of IWebHostBuilder.

DotNet Coding Specialist (DCS) — ASP.NET Core

The DotNet Coding Specialist certification validates hands-on .NET application development skills including ASP.NET Core middleware, dependency injection, authentication, configuration, and web API design using live-in-the-app question formats.

Questions

45 min

Time Limit

75%

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