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Dot Net Full Stack Developer Interview Questions and Answers

Published On: December 17, 2024

A Dot Net Full Stack Developer is proficient in both front-end and back-end development, utilizing technologies such as C#, ASP.NET, SQL Server, and modern JavaScript frameworks. Full-stack development in the .NET ecosystem involves creating web applications, managing databases, and integrating with different services. Preparing for Full Stack Dot Net Developer Interview Questions and Answers requires knowledge of key concepts such as MVC architecture, RESTful APIs, Entity Framework, and front-end technologies like React or Angular. Interview questions typically assess your ability to work across the entire stack, your understanding of software design principles, and your problem-solving skills.

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Dot Net Full Stack Developer Interview Questions for Freshers

1. What is the .NET Framework?

The .NET Framework is a software development platform developed by Microsoft, used for building and running applications on Windows. It includes a large class library, runtime environment (CLR), and supports multiple programming languages like C#, VB.NET, and F#.

2. What is the difference between .NET Core and .NET Framework?

Feature.NET Core.NET Framework
PlatformCross-platform (Windows, macOS, Linux)Windows-only
Development FocusModern applications, including cloud, IoT, and containersDesktop and large enterprise applications
Open SourceFully open sourcePartially open source
PerformanceHigh performance, optimized for cloud and microservicesSuitable for traditional applications
Target ApplicationsModern web, mobile, cloud, and microservicesWindows-based desktop and web applications
DeploymentFlexible (self-contained or framework-dependent)Requires installation on the target machine
Backward CompatibilityLimited to libraries compatible with .NET StandardBackward compatible with older .NET versions
Package ManagementNuGet-based with modular assemblyNuGet with a larger, monolithic framework
Language SupportSupports C#, F#, and VB.NETSupports C#, F#, and VB.NET
EcosystemContinually evolving with modern featuresStable, but less focus on new developments
Support for APIsSupports APIs in .NET Standard and new APIsComprehensive support for legacy APIs
ToolingVisual Studio, Visual Studio Code, CLI toolsVisual Studio
Release CycleRapid release cycle with regular updatesFixed, slower release cycle

3. Can you explain the role of CLR in .NET?

The Common Language Runtime (CLR) in .NET is the core runtime environment that manages the execution of .NET programs. It provides essential services like:

  • Code Execution – Runs your application code.
  • Memory Management – Handles allocation and garbage collection.
  • Security – Enforces code access and application security.
  • Exception Handling – Manages errors gracefully.
  • Interoperability – Allows communication between .NET and other languages or platforms.

4. What is a class in C#?

In C#, a class is a blueprint for creating objects. It specifies the data (properties) and functions (methods) that an object can include. Classes are used to encapsulate data and behavior, making code reusable and modular.

5. What is the difference between abstract and interface in C#?

FeatureAbstract ClassInterface
DefinitionA class that contains both abstract methods and concrete methods.A contract that only contains method and property declarations.
ImplementationCan provide partial implementation (concrete methods).Cannot provide any implementation (until C# 8.0). From C# 8.0, default implementations are allowed.
InheritanceSupports single inheritance (can inherit only one abstract class).Supports multiple inheritance (a class can implement multiple interfaces).
Access ModifiersCan have access modifiers for methods and properties.All methods and properties are implicitly public.
ConstructorsCan have constructors.Cannot have constructors.
FieldsCan contain fields (variables).Cannot contain fields, only properties.
When to UseUse when classes share a common base or default behavior.Use when defining a contract for unrelated classes.

6. What is inheritance in object-oriented programming?

Inheritance in object-oriented programming is a concept where one class (called the child or derived class) acquires the properties and behaviors of another class (called the parent or base class). It helps in reusing code and creating a hierarchical relationship between classes.

7. What is encapsulation in C#?

Encapsulation in C# is the process of bundling data (fields) and methods (functions) that operate on the data into a single unit, typically a class. It also restricts direct access to the internal details of a class, exposing only necessary parts through public methods or properties. This ensures data security and maintains control over how data is accessed or modified.

8. How do you handle exceptions in C#?

In C#, exceptions are handled using try-catch-finally blocks to prevent crashes and manage errors gracefully.

Key Parts:

  • try: Code that might throw an exception.
  • catch: Handles the exception.
  • finally: Runs cleanup code (optional).

Example:

try

{

    int number = int.Parse(“abc”); // Causes an error

}

catch (FormatException ex)

{

    Console.WriteLine($”Error: {ex.Message}”);

}

finally

{

    Console.WriteLine(“Done.”);

}

Output:

Error: Input string was not in a correct format.

Done.

This ensures safe and predictable code execution.

9. Explain the concept of polymorphism.

Polymorphism in C# means the ability for a method or object to take on many forms. It allows one method to behave differently based on the context.

Types:

  • Compile-Time Polymorphism (Method Overloading):

Same method name, different parameters.

public int Add(int a, int b) => a + b;

public double Add(double a, double b) => a + b;

  • Run-Time Polymorphism (Method Overriding):

Child class changes a method from the parent class.

class Animal { public virtual void Speak() => Console.WriteLine(“Animal”); }

class Dog : Animal { public override void Speak() => Console.WriteLine(“Bark”); }

Example:

Animal animal = new Dog();

animal.Speak();  // Output: Bark

Polymorphism lets methods behave differently based on the object type.

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10. What is the difference between == and Equals() in C#?

In C#, both == and Equals() are used for comparison, but they work differently:

Feature== OperatorEquals() Method
UsageUsed to compare values or object references.Used to compare object values (often overridden).
Default BehaviorChecks if two references point to the same object (for reference types) or if values are the same (for value types).Checks if the contents of two objects are the same (can be overridden in custom classes).
OverrideCannot be overridden (for reference types, compares reference by default).Can be overridden in custom classes to define how objects are compared.
Null HandlingWill throw an exception if comparing null with an object reference.Can be safely overridden to handle null.

11. What is the purpose of the using keyword in C#?

The using keyword in C# has two main purposes:

Namespace Import

It is used to include namespaces, making classes, methods, and other types available in the code without needing to specify the full namespace path.

using System;  // Importing the System namespace

class Program

{

    static void Main()

    {

        Console.WriteLine(“Hello, World!”); // System.Console is accessible without the full path

    }

}

Resource Management (Dispose Objects)

The using keyword is used to define a scope for objects that implement the IDisposable interface, ensuring that resources (like file handles or database connections) are automatically released when the object goes out of scope.

using (var file = new System.IO.StreamWriter(“example.txt”))

{

    file.WriteLine(“Hello, World!”);  // ‘file’ will be disposed of automatically when the block ends

}

In this case, the StreamWriter object is disposed of automatically at the end of the using block, freeing resources like file handles.

12. What is a delegate in C#?

A delegate in C# is a type that represents a method or a reference to a method. It allows you to pass methods as parameters and call them dynamically.

Key Points:

  • Type-safe: A delegate can only reference methods that match its signature.
  • Encapsulation: It allows methods to be passed as arguments, enabling callbacks and event handling.
  • Multicast: A delegate can reference multiple methods, allowing multiple methods to be called in sequence.

Example:

using System;

public delegate void PrintMessage(string message);  // Delegate declaration

class Program

{

    static void Main()

    {

        // Assign method to delegate

        PrintMessage print = PrintHello;

        print(“Hello, World!”);  // Calls PrintHello

        // Using delegate with anonymous method

        PrintMessage printAnon = delegate(string msg) { Console.WriteLine(msg); };

        printAnon(“Anonymous Method”);

    }

    static void PrintHello(string message)

    {

        Console.WriteLine(message);

    }

}

Output:

Hello, World!

Anonymous Method

In this example, PrintMessage is a delegate that can reference methods like PrintHello and an anonymous method.

13. Explain the concept of LINQ in .NET.

LINQ (Language Integrated Query) in .NET lets you easily query and work with data from different sources like collections, databases, and XML, all within C#. It uses a simple and consistent syntax for querying, no matter where the data comes from, and ensures the queries are checked for errors before running. For example, you can use LINQ to filter even numbers from an array in a clear and easy-to-understand way.

14. What is the purpose of the async and await keywords in C#?

The async and await keywords in C# are used to write asynchronous code, making it easier to handle tasks that take time, like downloading a file or querying a database, without blocking the main thread.

  • async: It marks a method as asynchronous, meaning it can run tasks in the background.
  • await: It tells the program to wait for the result of an asynchronous operation before continuing the execution.

How It Works:

  • async is used to define a method that will contain asynchronous operations.
  • await is used within an async method to pause the method’s execution until the awaited task completes.

Example:

using System;

using System.Threading.Tasks;

class Program

{

    static async Task Main()

    {

        Console.WriteLine(“Start”);

        await Task.Delay(2000);  // Simulate a delay (like waiting for a file to download)

        Console.WriteLine(“End”);

    }

}

Output:

Start

(Waits 2 seconds)

End

15. What is a constructor in C#?

A constructor in C# is a special method used to initialize an object when it is created.It shares the same name as the class and does not have a return type. Constructors can take parameters to set initial values for an object’s properties.

Example:

class Car

{

    public string Make { get; set; }

    public string Model { get; set; }

    // Constructor

    public Car(string make, string model)

    {

        Make = make;

        Model = model;

    }

}

class Program

{

    static void Main()

    {

        Car myCar = new Car(“Toyota”, “Corolla”);

        Console.WriteLine($”{myCar.Make} {myCar.Model}”);

    }

}

Output:

Toyota Corolla

In this example, the constructor initializes the Car object’s Make and Model when it’s created.

16. Explain the difference between a value type and a reference type.

FeatureValue TypeReference Type
Storage LocationStored in the stackStored in the heap
Examplesint, float, bool, structclass, string, array, delegate
Memory AllocationAllocated directly in memoryAllocated in heap, with a reference on stack
Default ValueHas a default value (e.g., 0, false)Default value is null
Assignment BehaviorCopy of the value is passedReference (memory address) is passed
ChangesChanges do not affect other copiesChanges affect all references to the object
LifetimeScoped to the method or blockLifetime is managed by garbage collection
InheritanceCannot inherit from other typesCan inherit from other types

17. What is MVC in .NET?

MVC (Model-View-Controller) in .NET is a design pattern used to build web applications by separating the application into three main components:

  • Model: Represents the application’s data and business logic.
  • View: Represents the user interface, showing data from the model to the user.
  • Controller: Handles user input, updates the model, and selects the view to display.

This separation of concerns helps in organizing code, making it easier to manage, maintain, and test. In .NET, the MVC pattern is widely used in ASP.NET MVC applications to build scalable and maintainable web applications.

18. What is the difference between MVC and WebForms?

FeatureMVCWebForms
ArchitectureFollows the Model-View-Controller patternBased on the event-driven page model
Control Over HTMLFull control over HTML markupLimited control; HTML generated by controls
Separation of ConcernsStrong separation of concerns (Model, View, Controller)Weaker separation, logic and presentation can be mixed
Page LifecycleExplicit control over the request/response cycleImplicit control; more abstracted lifecycle
URL MappingUses clean and customizable URLsURL mapping is based on file names
State ManagementNo built-in state management (stateless)Built-in state management (view state, session)
Data BindingManual data binding through controllers and viewsAutomatic data binding with controls
TestabilityHighly testable due to separation of concernsHarder to test due to tightly coupled code
Development ModelBetter suited for complex applications and APIsEasier for rapid development with drag-and-drop controls
Learning CurveSteeper due to manual control and configurationEasier for beginners due to abstraction and built-in controls

19. How does ASP.NET Core differ from ASP.NET?

FeatureASP.NETASP.NET Core
PlatformWindows-onlyCross-platform (Windows, Linux, macOS)
PerformanceSlower due to older architectureFaster and more efficient
DeploymentRequires IIS for hostingCan be hosted on IIS, Nginx, Apache, or self-hosted
FrameworkPart of the .NET Framework (Full Framework)Part of the .NET (Core) framework
ModularityLarger and less modularHighly modular, with smaller packages for better performance
Cross-Platform SupportNo cross-platform supportFull cross-platform support
ConfigurationUses web.config for configurationUses appsettings.json and environment variables
Dependency InjectionNot built-in, but can be added via third-party librariesBuilt-in dependency injection
HostingDependent on IIS or Windows ServerCan be hosted on any web server (IIS, Kestrel, etc.)
Updates and SupportOnly supports updates for WindowsActively developed with regular updates, including non-Windows platforms
Development and EcosystemOlder tools, less flexibility in modern developmentNewer tools and features, such as Visual Studio Code, with better support for modern workflows

20. What is a RESTful API?

A RESTful API is a web service that uses HTTP methods to interact with resources on a server. It follows these key principles:

  • Stateless: Each request is independent, and the server doesn’t store any data between requests.
  • HTTP Methods: Uses standard methods like GET (retrieve), POST (create), PUT (update), DELETE (remove).
  • Resources: Data is represented as resources, each with a unique URL.
  • Client-Server: The client (e.g., a browser or app) and server communicate separately.

For example, a GET /users/1 request retrieves information for user 1, while POST /users creates a new user. RESTful APIs are simple, scalable, and commonly used for web services.

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21. How do you implement CRUD operations in ASP.NET Core?

To implement CRUD operations (Create, Read, Update, Delete) in ASP.NET Core, you typically follow these steps:

  • Create a Model: Define a class representing the data structure (e.g., Product).
  • Create a Database Context: Use Entity Framework Core to interact with the database.
  • Create a Controller: Use the controller to define actions for each CRUD operation.
  • Create Views: Use Razor Views to create the user interface (UI) for each operation.

22. What is Entity Framework in .NET?

Entity Framework (EF) is an Object-Relational Mapping (ORM) framework for .NET that simplifies database interactions by allowing developers to work with data in the form of objects, rather than working with database tables and SQL queries directly. It automatically handles the conversion between C# objects and database records.

23. What is the difference between GET and POST HTTP methods?

FeatureGETPOST
PurposeRetrieves data from the server.Sends data to the server for processing.
Data in URLParameters are included in the URL (query string).Data is sent in the request body.
VisibilityData is visible in the browser’s address bar.Data is not visible in the address bar.
Data LengthLimited to the URL length (typically 2048 characters).No size limitation (limited by server configuration).
CachingCan be cached by the browser.Generally not cached.
IdempotenceSafe and idempotent (repeated requests do not change the state).Not necessarily idempotent (repeated requests may change data).
UsageUsed for retrieving data (e.g., search queries, accessing a webpage).Used for submitting data (e.g., form submissions, file uploads).
SecurityLess secure for sensitive data due to visibility in the URL.More secure because the data is transmitted in the body.

24. What is a session in ASP.NET?

A session in ASP.NET is a mechanism that allows you to store and manage user-specific data on the server for the duration of a user’s visit to a web application. It helps maintain state information across multiple requests from the same user, as HTTP is a stateless protocol.

25. How do you secure a web application in .NET?

Securing a web application in .NET involves several key practices:

  • Authentication & Authorization: Use ASP.NET Identity or OAuth for login, and control access with role-based or claim-based authorization.
  • Use HTTPS: Always use SSL/TLS to encrypt data between the client and server. Force HTTPS with RequireHttps.
  • Input Validation: Validate all user inputs to prevent SQL Injection and XSS attacks. Use data annotations and regex for validation.
  • CSRF Protection: Use anti-forgery tokens (@Html.AntiForgeryToken()) to prevent Cross-Site Request Forgery.
  • Session Management: Use secure cookies with HttpOnly and Secure flags. Set reasonable session timeouts.
  • Encryption: Encrypt sensitive data (like passwords) using AES or ASP.NET’s Data Protection API.
  • Secure Configuration: Store sensitive data (e.g., API keys) securely in environment variables or Azure Key Vault. Avoid detailed error messages in production.
  • Rate Limiting: Use rate limiting to prevent brute-force attacks.
  • Patching & Updates: Keep .NET, libraries, and the server environment updated to avoid vulnerabilities.
  • Logging & Monitoring: Log security events and monitor for suspicious activities.
  • Content Security Policy: Use CSP headers to restrict which resources can load on your site.

Dot Net Full Stack Developer Interview Questions For Experienced:

1. Explain the difference between IEnumerable and IQueryable.

FeatureIEnumerableIQueryable
DefinitionRepresents a collection of objects that can be traversed.Represents a collection of data that can be queried from a data source, like a database.
ExecutionData is retrieved in memory (in-memory collection).Data is queried from a data source, like a database, using LINQ-to-SQL or LINQ-to-Entities.
EvaluationImmediate execution – Executes the query as soon as it’s called.Deferred execution – Executes the query only when the data is enumerated or iterated.
UsageBest used for in-memory collections like lists, arrays.Best used for database queries or remote data sources where filtering is required.
PerformanceLoads all data into memory, which can be inefficient for large datasets.Efficient for large datasets because it translates LINQ queries into optimized SQL commands, limiting data loading.
Where to UseUse for local collections (e.g., arrays, lists, dictionaries).Use for remote data sources, especially databases (SQL, Entity Framework).
MethodsSupports LINQ to Objects methods like Where, Select.Supports LINQ to Entities or LINQ to SQL methods, enabling queries to be executed directly on the data source.

2. What is dependency injection in ASP.NET Core?

Dependency Injection (DI) in ASP.NET Core is a pattern where dependencies are provided to a class rather than created inside it, improving modularity and testability. Services are registered in Startup.cs with lifetimes like Transient (new per request), Scoped (one per request), or Singleton (one for the app). These services are injected into classes, such as controllers, using constructors. DI simplifies configuration, reduces coupling, and makes it easier to test applications.

3. What are middleware components in ASP.NET Core?

Middleware in ASP.NET Core are components in the HTTP pipeline that handle requests and responses. They can perform tasks like authentication, routing, logging, or error handling. Middleware is executed in the order it’s added in Startup.cs. For example, built-in middleware like UseRouting and UseAuthentication handle routing and user authentication. You can also create custom middleware to add specific functionality, making the app modular and easy to manage.

4. How does Entity Framework Core differ from Entity Framework?

AspectEntity Framework (EF)Entity Framework Core (EF Core)
PlatformWorks only on .NET Framework (Windows).Cross-platform, runs on .NET Core and .NET Framework.
PerformanceSlower compared to EF Core.Faster due to improved architecture and optimizations.
FeaturesMature, but lacks support for some modern database features.Lightweight, supports modern features like LINQ improvements, batch updates.
Database SupportLimited to SQL Server, Oracle, and a few others.Supports SQL Server, SQLite, MySQL, PostgreSQL, and more.
MigrationSupports migrations but less flexible.Advanced and more flexible migrations.
Future UpdatesNo longer actively developed.Actively maintained and improved.

5. Can you explain the life cycle of a request in ASP.NET Core?

In ASP.NET Core, a request goes through these steps:

  • Request Arrival: The web server (e.g., Kestrel) receives the request and passes it to the app.
  • Middleware Pipeline: The request flows through middleware components (e.g., for logging, authentication, routing).
  • Routing: The routing middleware matches the request to a controller or endpoint.
  • Controller Action: The matched action executes, processes the request, and prepares a response.
  • Response Return: The response passes back through middleware for final processing and is sent to the client.

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6. How do you handle logging in ASP.NET Core applications?

In ASP.NET Core, you can handle logging with these simple steps:

  • Configure Logging: Set log levels in the appsettings.json file.
    Example:

“Logging”: { “LogLevel”: { “Default”: “Information” } }

  • Add Logging in Code: Use ILogger to log messages in your application.
    Example:

_logger.LogInformation(“Page loaded.”);

  • Use Providers: ASP.NET Core supports built-in providers (console, debug) and third-party tools like Serilog or NLog.
  • Customize: Create custom logging if needed, like logging to a database.

7. Explain the concept of asynchronous programming in .NET.

Asynchronous programming in .NET allows tasks to run in the background without stopping the main program. Using the async keyword makes a method run asynchronously, and the await keyword waits for a task to finish without blocking other tasks. This helps when performing tasks like fetching data from the internet or reading files, as the program can keep doing other things while waiting. For example, an async method can get data from a website without freezing the app, making it faster and more responsive.

8. What is a microservice architecture, and how does it relate to .NET Core?

A microservice architecture is a way of building an application using small, separate services that communicate over a network. Each service performs a specific task and can be developed, deployed, and scaled on its own.

In a microservice architecture:

  • Services are loosely coupled, meaning changes in one s   ervice don’t affect others.
  • Each service can be built using different technologies and databases, but they communicate through standard protocols like HTTP/REST or messaging queues.
  • Services are deployable independently, enabling faster updates and scaling.

How it relates to .NET Core:

  • Cross-platform: .NET Core is ideal for building microservices because it runs on Windows, Linux, and macOS, allowing flexibility in deploying across different environments.
  • Performance: .NET Core is lightweight and fast, making it suitable for high-performance microservices.
  • Modularity: .NET Core allows you to break down applications into smaller, independent services that can be easily developed and maintained.
  • Built-in Support: .NET Core has built-in libraries and tools for creating REST APIs, handling communication, and managing dependencies, all of which are important in a microservices-based system.

9. How do you implement JWT authentication in a .NET Core application?

To implement JWT authentication in a .NET Core app:

  • Install Packages: Add Microsoft.AspNetCore.Authentication.JwtBearer.
  • Configure Authentication: In Program.cs, set up JWT authentication:

services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)

        .AddJwtBearer(options =>

        {

            options.TokenValidationParameters = new TokenValidationParameters

            {

                ValidateIssuer = true,

                ValidateAudience = true,

                ValidateLifetime = true,

                ValidateIssuerSigningKey = true,

                ValidIssuer = “your-issuer”,

                ValidAudience = “your-audience”,

                IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(“your-secret-key”))

            };

        });

  • Generate Token: Create a method to generate JWT tokens:


public string GenerateToken()

{

    var claims = new[] { new Claim(JwtRegisteredClaimNames.Sub, “user-id”) };

    var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(“your-secret-key”));

    var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);

    var token = new JwtSecurityToken(“your-issuer”, “your-audience”, claims,

                                     expires: DateTime.Now.AddMinutes(30), signingCredentials: creds);

    return new JwtSecurityTokenHandler().WriteToken(token);

}

  • Protect Endpoints: Add [Authorize] to controllers or actions:

    [Authorize]

public IActionResult GetSecureData() => Ok(“Secure data!”);

  • Test: Pass the token in the Authorization header:
    Authorization: Bearer <token>.

This secures your APIs by verifying JWT tokens during requests.

10. What is the role of the appsettings.json file in ASP.NET Core?

The appsettings.json file in ASP.NET Core is used to store application configuration settings in a structured, JSON format. It typically includes settings like connection strings, logging configurations, API keys, and other environment-specific values. The file is automatically loaded at runtime, and its data can be accessed through the configuration system provided by ASP.NET Core.

For example, you can retrieve settings using dependency injection or the Configuration object. You can also use environment-specific files like appsettings.Development.json to override values for different environments. This approach simplifies managing and updating configuration without changing the application code.

11. How do you implement custom validation in ASP.NET Core MVC?

To implement custom validation in ASP.NET Core MVC:

Create a Custom Attribute:

Inherit from ValidationAttribute and override IsValid:

public class CustomAgeAttribute : ValidationAttribute

{

    protected override ValidationResult IsValid(object value, ValidationContext context)

       {

        return (value is int age && age >= 18) 

            ? ValidationResult.Success 

            : new ValidationResult(“Age must be 18 or above.”);

    }

}

Apply to Model:

Use the custom attribute in your model:

public class UserModel

{

    [CustomAge]

    public int Age { get; set; }

}

Validate in Controller:
Check ModelState.IsValid in your controller:

if (ModelState.IsValid) return View(“Success”);

Show Errors in View:
Use asp-validation-for to display errors in the form:

<input asp-for=”Age” />

<span asp-validation-for=”Age”></span>

This adds custom validation to your model effortlessly.

12. What is the role of caching in web applications, and how do you implement it in .NET Core?

Caching speeds up web apps by storing frequently used data temporarily, reducing database calls and server load, and improving performance.

Implementing Caching in .NET Core

Enable Caching:

Add services.AddMemoryCache() in Program.cs.

Use Memory Cache:

Inject IMemoryCache and store or retrieve cached data:


if (!_cache.TryGetValue(“key”, out string data))

{

    data = “Cached Data”;

    _cache.Set(“key”, data, TimeSpan.FromMinutes(10));

}

return Content(data);

Response Caching:

Use response caching middleware:


app.UseResponseCaching();

Add [ResponseCache(Duration = 60)] to controllers for caching responses.

This reduces redundant processing and speeds up responses.

13. Explain the concept of Razor Pages in ASP.NET Core.

Razor Pages in ASP.NET Core is a simplified framework for building server-side web applications. It focuses on page-based development, where each page is self-contained with its own UI logic and behavior. Razor Pages use .cshtml files for markup and a backing PageModel class for server-side logic.

14. How do you handle cross-origin requests (CORS) in ASP.NET Core?

CORS allows your app to accept requests from other origins. Here’s how to enable it:

Add CORS in Services:
In Program.cs:

services.AddCors(options =>

{

    options.AddPolicy(“AllowOrigin”, policy =>

        policy.WithOrigins(“https://example.com”)

              .AllowAnyHeader()

              .AllowAnyMethod());

});

Use CORS Middleware:
Enable the policy in the pipeline:


app.UseCors(“AllowOrigin”);

Apply to Controllers:

Use [EnableCors(“AllowOrigin”)] on specific controllers or actions.

Allow All Origins (Optional):
Use AllowAnyOrigin, AllowAnyHeader, and AllowAnyMethod for all access.

This controls cross-origin requests securely.

15. What is SignalR in .NET?

SignalR in .NET is a library used to build real-time web applications. It enables servers to push updates to connected clients instantly, without requiring the clients to request data repeatedly. SignalR is commonly used for applications like chat systems, live notifications, or collaborative tools.

Check out: VB Dot Net Course in Chennai

16. How do you implement security in a REST API in ASP.NET Core?

To secure a REST API in ASP.NET Core, you can follow these steps:

  • Enable HTTPS: Use app.UseHttpsRedirection() for secure communication.
  • Authentication and Authorization:
  • Use JWT for user authentication.
  • Restrict access with [Authorize] attributes.
  • Validate Inputs: Ensure inputs are safe to prevent attacks like SQL injection.
  • Configure CORS: Restrict access to trusted origins.
  • Implement Rate Limiting: Prevent abuse by limiting client requests.
  • Secure Data: Hash sensitive data and use secure headers.
  • Monitor Activity: Log and monitor requests for suspicious behavior.

17. Explain the concept of the Repository Pattern in .NET.

The Repository Pattern in .NET is a design pattern that creates a layer between business logic and data access, ensuring separation of concerns. It abstracts data access details, making the code more reusable and testable. For example, you can define a repository interface with methods like GetAll, GetById, Add, Update, and Delete, then implement it using a data access technology like Entity Framework. This approach centralizes data access logic, making it easier to manage and test while keeping the business logic clean and focused.

18. How would you optimize the performance of a .NET application?

Improve your .NET application’s performance with these strategies:

  1. Write Efficient Code:
    • Minimize redundant computations and avoid unnecessary loops.
    • Use asynchronous methods for tasks like I/O operations.
  1. Optimize Database Operations:
    • Use parameterized queries and stored procedures.
    • Implement caching for frequently accessed data.
  1. Leverage Caching: Cache frequently used data or results to reduce processing time.
  1. Manage Memory Effectively:
    • Properly dispose of unmanaged resources.
    • Prevent memory leaks by freeing up resources when you’re done using them.
  1. Compress and Bundle Files: Reduce the size of CSS, JavaScript, and other static assets to improve loading times.
  1. Use Profiling Tools: Identify performance bottlenecks with tools like Visual Studio Profiler or JetBrains dotTrace.
  1. Enable HTTP/2: Improve network efficiency by switching to HTTP/2 for faster communication.
  1. Reduce Dependencies: Keep libraries and external dependencies lightweight and essential.

19. What are ValueTask and Task in asynchronous programming?

FeatureTaskValueTask
PurposeRepresents an asynchronous operation.Optimized for lightweight or cached results.
AllocationAlways allocates memory.Avoids allocation if the result is available immediately.
ReusabilitySingle-use; cannot be reused.Can be reused for multiple calls.
Use CaseSuitable for most async operations.Ideal for performance-critical scenarios with frequent synchronous results.
ComplexitySimple to use and handle.Requires careful use to avoid performance issues or bugs.

When to Use:

  • Use Task for general-purpose async programming.
  • Use ValueTask when performance is critical, and you expect frequent synchronous results.

20. What is the purpose of the ConfigureServices method in ASP.NET Core?

The ConfigureServices method in ASP.NET Core is used to register services and configure dependency injection (DI) for the application. It allows you to add services like controllers, database contexts, authentication, and custom services to the DI container. These services can then be easily injected into controllers or other components, promoting modularity and maintainability. For example, you can configure MVC, register a database context, or add custom business logic services in this method.

21. How would you implement versioning in an API?

To implement versioning in an API, you can use different strategies based on your application’s needs:

  1. URL Path Versioning: Include the version in the URL, such as /api/v1/resource.
  1. Query String Versioning: Add the version as a query parameter, e.g., /api/resource?version=1.
  1. Header Versioning: Specify the version in the request header, like X-API-Version: 1.
  1. Content Negotiation: Use the Accept header with media types, such as application/vnd.myapi.v1+json.

22. What are the advantages of using Azure DevOps for .NET Core applications?

Azure DevOps offers several advantages for .NET Core applications:

  • Streamlined Development: It combines tools for planning, coding, testing, and deploying in one platform, reducing the need for multiple tools.
  • CI/CD Pipelines: It automates the build, testing, and deployment processes, accelerating delivery and ensuring more reliable releases.
  • Cloud Integration: Azure DevOps integrates seamlessly with Azure, as well as other cloud services, making it a versatile choice for cloud-based apps.
  • Collaboration: It enhances teamwork with features like boards, wikis, and shared repositories, improving project tracking and communication.
  • Scalability: Azure DevOps handles projects of all sizes efficiently, thanks to its distributed agents and robust infrastructure.
  • Monitoring: It offers integrated tools for monitoring app performance and collecting user feedback, enabling better decision-making.

23. Can you explain the differences between SQL Server and NoSQL databases?

FeatureSQL ServerNoSQL
Data StructureRelational (tables with rows and columns)Non-relational (key-value, document, graph, etc.)
SchemaFixed schema, requires predefined structureFlexible schema, allows unstructured data
ScalabilityScales vertically (adding power to a single server)Scales horizontally (distributes data across servers)
TransactionsACID-compliant (strong consistency)BASE-compliant (eventual consistency, flexible)
Query LanguageSQL (Structured Query Language)Various query languages (e.g., MongoDB query language)
Use CasesComplex queries, transactions, strict consistency (e.g., banking, enterprise apps)High scalability, unstructured data, real-time apps (e.g., social media, big data)
ExamplesMicrosoft SQL Server, MySQL, PostgreSQLMongoDB, Cassandra, Redis, Couchbase

24. How do you manage configuration settings in .NET Core applications?

In .NET Core, configuration settings are managed using various methods:

  • appsettings.json: Stores settings like connection strings and API keys in JSON format.
  • Environment Variables: Used for sensitive data and can override settings in appsettings.json.
  • Command-line Arguments: Pass settings at startup, overriding other sources.
  • Secrets Management: For development, sensitive data can be stored securely using User Secrets.
  • Configuration API: The IConfiguration interface loads settings from all sources, which can be accessed in services.
  • Azure App Configuration: For cloud applications, centralize and manage settings in Azure.

These methods provide flexibility for loading and overriding configuration across different environments.

25. What are the different types of joins in SQL, and how are they used in Entity Framework?

In SQL, there are several types of joins used to combine data from different tables:

  • INNER JOIN: Returns only the matching rows from both tables.
    • Example: SELECT * FROM Orders INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID;
  • LEFT JOIN: Returns all rows from the left table, along with matched rows from the right table. If there is no match, NULL values are returned for the right table.
    • Example: SELECT * FROM Orders LEFT JOIN Customers ON Orders.CustomerID = Customers.CustomerID;
  • RIGHT JOIN: Returns all rows from the right table, along with matched rows from the left table. If there is no match, NULL values are returned for the left table.
    • Example: SELECT * FROM Orders RIGHT JOIN Customers ON Orders.CustomerID = Customers.CustomerID;
  • FULL OUTER JOIN: Returns rows when there is a match in either table. If no match exists, NULL values are returned.
    • Example: SELECT * FROM Orders FULL OUTER JOIN Customers ON Orders.CustomerID = Customers.CustomerID;
  • CROSS JOIN: Returns all possible combinations (Cartesian product) of rows from both tables.
    • Example: SELECT * FROM Orders CROSS JOIN Customers;

When using Entity Framework, joins are typically done with LINQ:

INNER JOIN: Achieved using a simple join clause in LINQ.

Example:
var result = from order in context.Orders

             join customer in context.Customers on order.CustomerID equals customer.CustomerID

             select new { order, customer };

LEFT JOIN: Done using join with into and DefaultIfEmpty to handle missing matches.

Example:
var result = from order in context.Orders

             join customer in context.Customers on order.CustomerID equals customer.CustomerID into orderGroup

             from customer in orderGroup.DefaultIfEmpty()

             select new { order, customer };

RIGHT JOIN: Not directly supported in EF, but can be simulated with a left join in reverse.

FULL OUTER JOIN: Not directly supported in EF, but can be simulated by combining left and right joins.

CROSS JOIN: Simulated by using multiple from clauses in LINQ.

Example:

var result = from order in context.Orders

             from customer in context.Customers

             select new { order, customer };

While EF typically uses navigation properties for relationships, explicit joins like these are sometimes needed for more complex queries.

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Conclusion

In conclusion, to succeed in a Dot Net Full Stack Developer Interview and Questions, you need strong knowledge of both front-end and back-end technologies, including ASP.NET Core, C#, Entity Framework, and SQL. Key topics often covered include object-oriented programming (OOP), design patterns, RESTful APIs, and database management.

Familiarity with front-end technologies like HTML, CSS, JavaScript, and frameworks like Angular or React is also essential. Additionally, understanding version control, CI/CD pipelines, and tools like Azure DevOps will be helpful. Focus on your technical skills, problem-solving ability, and teamwork experience to perform well in Dot Net Full Stack Developer Interview and Questions.

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