Interview Q&A

Answer: Inject services into PageModel constructor: public IndexModel(IMyService service) { ... } Also available in Razor views via @inject: @inject ILogger<MyPage> Logger

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Answer: Reusable libraries that contain Razor views, pages, static files, etc. Share UI components across multiple projects. dotnet new razorclasslib

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Answer: Used to organize large applications into sections (e.g., Admin, Customer). Each Area has its own Controllers/Views/Models. [Area("Admin")] public class DashboardController : Controller { ... }

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Answer: Handled via: ASP.NET Core Middleware WebOptimizer, Gulp, or Webpack Static files in wwwroot/ Enable in Startup.cs: app.UseStaticFiles();

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Answer: ASP.NET Core supports Razor by default. You can add support for custom view engines by implementing IViewEngine.

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Answer: Use IStringLocalizer<T> or IViewLocalizer: @inject IViewLocalizer Localizer <h1>@Localizer["Welcome"]</h1> Add resource .resx files for each language.

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

• Performance: Very similar, both use Razor rendering.
• Simplicity: Razor Pages have less boilerplate for page-based UIs.
• Maintainability: Razor Pages better for small apps, MVC better for

large, modular apps.

Web API (RESTful Services)

Web API (RESTful Services)

REST (Representational State Transfer) is an architectural style for

building scalable web services. RESTful APIs follow standard HTTP

methods (GET, POST, PUT, DELETE) and stateless communication.

✅ Key principles for RESTful API in ASP.NET Core:

• Use HTTP verbs for operations.
• Use nouns (resources) in URIs, not verbs.
• Support stateless operations.
• Return appropriate HTTP status codes.
• Implement HATEOAS (optional for hypermedia).

How to design RESTful APIs in ASP.NET Core

REST (Representational State Transfer) is an architectural style for

building scalable web services. RESTful APIs follow standard HTTP

methods (GET, POST, PUT, DELETE) and stateless communication.

✅ Key principles for RESTful API in ASP.NET Core:

• Use HTTP verbs for operations.
• Use nouns (resources) in URIs, not verbs.
• Support stateless operations.
• Return appropriate HTTP status codes.
• Implement HATEOAS (optional for hypermedia).

Answer: SP.NET Core. ✅ Benefits: Automatic model validation Infer [FromBody] / [FromQuery], etc. 400 BadRequest returned automatically if model state is invalid. Improved parameter binding behavior

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

The [ApiController] attribute is used to denote Web API controllers in

ASP.NET Core.

✅ Benefits:

• Automatic model validation
• Infer [FromBody] / [FromQuery], etc.
• 400 BadRequest returned automatically if model state is invalid.
• Improved parameter binding behavior

templates)

• Attribute Routing (Preferred):

[Route("api/products")]

[ApiController]

public class ProductsController : ControllerBase {

[HttpGet("{id}")]

public IActionResult Get(int id) { ... }
}

• Route Templates:

Use placeholders like {id}, constraints like {id:int}.

You can also define route prefixes at controller level and use relative routes

in actions.

Answer: pplication/vnd.company.v1+json services.AddApiVersioning(options => { options.ReportApiVersions = true; options.AssumeDefaultVersionWhenUnspecified = true; options.DefaultApiVersion = new ApiVersion(1, 0); });

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

media type versioning)

Use Microsoft.AspNetCore.Mvc.Versioning package.

✅ Supported methods:

• URL versioning: /api/v1/products
• Header versioning: X-API-Version: 1.0
• Media Type versioning: Accept:

application/vnd.company.v1+json

services.AddApiVersioning(options => {

options.ReportApiVersions = true;

options.AssumeDefaultVersionWhenUnspecified = true;

options.DefaultApiVersion = new ApiVersion(1, 0);

});

Answer: SP.NET Core selects the response format based on the Accept header. JSON is the default. To add XML: services.AddControllers() .AddXmlSerializerFormatters(); ccept: application/xml

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

SP.NET Core infers the source when possible.

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Answer: form Source Attribute Body [FromBody Query string [FromQuer Route [FromRout Form data [FromForm Header [FromHear ASP.NET Core infers the source when possible.

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Answer: For large uploads, use IFormFile, Stream, or read from Request.Body for streaming. For downloads, return FileStreamResult. Enable buffering or streaming to avoid memory overload.

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Answer: pp.UseExceptionHandler(config => { config.Run(async context => { // Log and return problem details }); }); Or use ProblemDetails for structured error responses.

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Use UseExceptionHandler middleware or custom ExceptionMiddleware.

You can also create a global error handler:

app.UseExceptionHandler(config => {

config.Run(async context => {

// Log and return problem details

});

});

Or use ProblemDetails for structured error responses.

Use proper status codes:

• 200 OK (success)
• 201 Created (on POST)
• 204 No Content (on DELETE)
• 400 Bad Request
• 401 Unauthorized / 403 Forbidden
• 404 Not Found
• 500 Internal Server Error

return Ok(result);
return NotFound();
return BadRequest(ModelState);

• ActionResult<T>: Combines a return value and response code.

public ActionResult<Product> Get(int id) { ... }

• IActionResult: More flexible, returns different result types explicitly.

Prefer ActionResult<T> for simpler, strongly-typed APIs.

SP.NET Core supports full async/await pattern for IO-bound tasks.

[HttpGet]

public async Task<ActionResult<Product>> GetAsync(int id) {
var product = await _repo.GetAsync(id);
return product == null ? NotFound() : Ok(product);
}

✅ Improves scalability and performance.

NotFound() : Ok(product); ✅ Improves scalability and performance.

What interviewers expect

• A clear definition tied to ASP.NET Core in ASP.NET Core projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production ASP.NET Core application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in ASP.NET Core architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.

Enable CORS (Cross-Origin Resource Sharing) to allow client apps from

different domains:

services.AddCors(options => {

options.AddPolicy("AllowFrontend", builder =>

builder.WithOrigins("

.AllowAnyHeader()

.AllowAnyMethod());

});

app.UseCors("AllowFrontend");