.Net Interview Questions for fresher with Answers

.Net Interview Questions for fresher with Answers -.NET is a software development framework created by Microsoft, used to build a wide range of applications, from web to desktop and mobile. For freshers, .NET interview questions typically focus on the basics of the .NET framework, its architecture, and core components such as the Common Language Runtime (CLR) and the .NET class library. You may be asked about your understanding of programming languages like C# or VB.NET, and how .NET supports multiple languages through the CLR.

Common topics include object-oriented programming (OOP) concepts like inheritance, polymorphism, encapsulation, and abstraction. You may also encounter questions on the differences between .NET Framework and .NET Core, handling exceptions, using collections, and working with databases via ADO.NET or Entity Framework. Understanding the basics of ASP.NET for web development, along with front-end technologies like HTML, CSS, and JavaScript, can also be useful. Additionally, knowledge of Visual Studio as an integrated development environment (IDE) is often expected.

Here the most important  .Net Interview Questions for fresher with Answers .

1.What is .NET Framework?

The .NET Framework is a software development platform developed by Microsoft. It provides a large library of pre-built class libraries and supports multiple programming languages like C#, VB.NET, and F#. The framework simplifies the development of applications by providing a runtime environment, known as the Common Language Runtime (CLR), and a comprehensive set of libraries for tasks like file handling, database access, and web development.

2.What is the CLR in .NET?

The Common Language Runtime (CLR) is the virtual machine component of the .NET Framework. It provides services like memory management, garbage collection, exception handling, and type safety. The CLR allows code written in different .NET languages to be executed on any system that has the .NET Framework installed, making the application platform-independent.

3.What is C#?

C# (pronounced as C-Sharp) is a modern, object-oriented programming language developed by Microsoft within the .NET ecosystem. It is used to build a variety of applications, including web applications, desktop applications, mobile apps, and games. It combines the power of C++ with the simplicity of Java, making it one of the most widely used languages for enterprise-level applications.

4.What is ASP.NET?

ASP.NET is a web development framework in the .NET platform that allows developers to create dynamic web pages, applications, and services. It supports multiple development models, including MVC (Model-View-Controller) and Web Forms. ASP.NET simplifies tasks like form handling, session management, and authentication, providing a robust solution for web-based applications.

5.What is ASP.NET MVC?

ASP.NET MVC is a framework used for building web applications using the Model-View-Controller design pattern. In this architecture, the Model represents the data, the View displays the data, and the Controller manages user interaction. ASP.NET MVC promotes separation of concerns and makes web applications more modular, easier to maintain, and testable.

6.What is .NET Core?

.NET Core is an open-source, cross-platform version of the .NET Framework, allowing developers to build applications that run on Windows, Linux, and macOS. It is optimized for performance and scalability, making it suitable for microservices, cloud-based applications, and enterprise applications. .NET Core is the future of the .NET platform and has evolved into .NET 5 and beyond.

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

The main difference between .NET Framework and .NET Core is that the .NET Framework is designed for Windows-only applications, while .NET Core is cross-platform and runs on Windows, Linux, and macOS. .NET Core is also lightweight, modular, and more suited for cloud and microservices architectures.

8.What are Assemblies in .NET?

An Assembly is a compiled code library in .NET that contains one or more namespaces and classes. Assemblies are the building blocks of a .NET application, providing a way to manage code deployment, versioning, and security. They come in two types: DLL (Dynamic Link Library) for shared code, and EXE for executables.

9.What is the GAC (Global Assembly Cache)?

The Global Assembly Cache (GAC) is a special folder in the .NET Framework where shared assemblies are stored. Assemblies that are intended to be used by multiple applications on a machine are installed in the GAC. The GAC helps in versioning and ensures that applications can reference the correct version of an assembly.

10.What is Managed Code in .NET?

Managed code is code that runs under the control of the Common Language Runtime (CLR) in the .NET environment. The CLR provides services like memory management, security, and exception handling, making managed code more secure and easier to debug. In contrast, unmanaged code is executed directly by the operating system.

11.What are the advantages of using .NET?

Some key advantages of using .NET include:

• Cross-platform development (with .NET Core).
• Support for multiple programming languages.
• Rich class library and built-in functionalities.
• Robust memory management through garbage collection.
• Improved security features.
• Support for modern development paradigms like REST APIs, Microservices, and Cloud.

12.What is Garbage Collection in .NET?

Garbage Collection (GC) is an automatic memory management feature of the CLR that reclaims memory occupied by unused objects. The GC operates in the background and runs when the system is low on memory. It helps prevent memory leaks and optimizes the application’s memory usage.

13.What are Value Types and Reference Types in .NET?

In .NET, Value Types store data directly in memory, and their values are stored in the stack (e.g., int, float, bool). Reference Types store a reference to the actual data, and their values are stored in the heap (e.g., class, object, string). Understanding this distinction helps in managing memory usage efficiently.

14.What is the difference between Stack and Heap?

The Stack is a region of memory used for static memory allocation. It stores value types and reference pointers. The Heap is used for dynamic memory allocation, and it stores objects created with new. The Stack has faster access times but limited size, while the Heap can store more data but is slower.

15.What is LINQ?

LINQ (Language Integrated Query) is a feature in .NET that allows developers to write queries directly in C# or VB.NET to retrieve data from various sources like collections, databases, or XML. LINQ provides a uniform way to interact with different data sources, reducing code complexity and increasing readability.

16.What is the Entity Framework (EF)?

Entity Framework (EF) is an Object-Relational Mapping (ORM) tool in .NET that simplifies database operations. EF allows developers to work with databases using .NET objects (entities) instead of writing SQL queries. It supports LINQ to Entities for querying data and provides features like code-first and database-first approaches.

17.What is Dependency Injection in .NET?

Dependency Injection (DI) is a design pattern used in .NET to achieve loose coupling between classes. Instead of creating objects within a class, the objects are injected into the class through constructors, methods, or properties. DI is widely used in frameworks like ASP.NET Core to manage services and dependencies.

18.What are the different types of JIT (Just-in-Time) compilation in .NET?

The .NET Framework uses Just-in-Time (JIT) compilation to convert MSIL (Microsoft Intermediate Language) into native code. There are three types of JIT:

• Normal JIT: Compiles code when it’s called for the first time.
• Econo JIT: Compiles code in a way that reduces memory usage.
• Pre-JIT: Compiles the entire code before execution (used in NGEN).

19.What is ASP.NET Web API?

ASP.NET Web API is a framework that allows developers to build RESTful services over HTTP. It is used to create services that can be consumed by web applications, mobile apps, and IoT devices. Web API supports JSON and XML as the data formats and is ideal for stateless applications.

20.What are Middleware components in ASP.NET Core?

In ASP.NET Core, middleware are components that are assembled into an HTTP request pipeline to handle requests and responses. Each middleware can either process the incoming request or pass it on to the next middleware. Common middleware includes Authentication, Routing, Exception Handling, and Static Files.

21.What is a ViewModel in ASP.NET MVC?

A ViewModel in ASP.NET MVC is a class that represents the data needed for rendering a View. It acts as a bridge between the Model and the View, containing properties that the view will bind to. The use of ViewModels helps maintain a clean separation between the data layer and the presentation layer.

22.What is Razor in ASP.NET?

Razor is a view engine in ASP.NET MVC that allows developers to write server-side code (C# or VB.NET) in HTML pages. Razor syntax is clean and lightweight, offering an easy way to integrate dynamic content into web pages. Razor views end with .cshtml (for C#) or .vbhtml (for VB.NET).

23.What is .NET Standard?

.NET Standard is a formal specification of APIs that all .NET implementations must provide. It ensures that different versions of .NET, such as .NET Framework, .NET Core, and Xamarin, can use the same set of libraries. This enhances code reusability and helps developers build applications across different platforms.

24.What is the role of NuGet in .NET?

NuGet is a package manager for .NET, which provides a way to share and consume code libraries across projects. Developers can easily install, update, and manage dependencies by using NuGet packages, which are stored in repositories like nuget.org. NuGet simplifies code sharing and helps in managing library versions.

25.What is Kestrel in ASP.NET Core?

Kestrel is a cross-platform web server included with ASP.NET Core. It is lightweight and highly efficient, making it suitable for both development and production environments. While Kestrel can handle most scenarios, it is often used with reverse proxies like IIS or NGINX for additional features like security and load balancing.

26.What is the difference between Task and Thread in .NET?

In .NET, a Thread is a unit of execution that runs in parallel, directly managed by the operating system. A Task is a higher-level abstraction built on top of Threads that simplifies asynchronous programming and is managed by the Task Parallel Library (TPL). While both represent parallel work, Tasks offer more flexibility and features, such as continuations, cancellation, and better error handling.

27.What is asynchronous programming in .NET?

Asynchronous programming in .NET allows for non-blocking code execution, enabling programs to perform other tasks while waiting for long-running operations (like I/O operations) to complete. This is achieved using the async and await keywords, which simplify the writing of asynchronous methods and improve performance in web applications or services where responsiveness is critical.

28.What is the difference between Abstract Class and Interface in .NET?

An Abstract Class can have both abstract (without implementation) and concrete methods (with implementation), while an Interface can only declare methods or properties without providing any implementation. Abstract classes are used for inheritance hierarchies, while interfaces define contracts that classes must implement. A class can inherit from one abstract class but implement multiple interfaces.

29.What is the .NET MAUI?

.NET MAUI (Multi-platform App UI) is a cross-platform framework that allows developers to build applications for iOS, Android, Windows, and macOS using a single codebase. It is the evolution of Xamarin.Forms and part of .NET 6+. It enables the development of rich UI applications, providing a unified UI toolkit and a simplified approach for cross-platform development.

30.What are Generics in .NET?

Generics in .NET allow developers to define classes, methods, and interfaces with type parameters, which means that the same code can work with any data type. Generics improve type safety, reusability, and performance by eliminating the need for boxing and unboxing. They are commonly used in collections (e.g., List<T>) and other data structures.

31.What is the role of IL (Intermediate Language) in .NET?

Intermediate Language (IL) is the low-level, platform-independent instruction set used by .NET languages (e.g., C# or VB.NET) after compilation. Code written in .NET languages is first compiled into IL and then converted into machine code by the JIT (Just-In-Time) compiler during runtime. IL enables cross-language interoperability within the .NET environment.

32.What is the difference between Overriding and Overloading in C#?

Overriding refers to modifying the implementation of a method in a derived class that was originally defined in a base class using the override keyword. Overloading occurs when multiple methods in the same class have the same name but different parameters (e.g., method signatures). Overriding is related to polymorphism, while overloading improves code readability.

33.What is a Singleton Pattern in .NET?

The Singleton Pattern ensures that a class has only one instance throughout the application’s lifecycle and provides a global point of access to that instance. This pattern is useful for classes that handle logging, configuration settings, or database connections. In .NET, it can be implemented by creating a static property or method that returns the single instance.

34.What is the use of IDisposable Interface in .NET?

The IDisposable interface defines a Dispose method that developers can implement to release unmanaged resources like file handles, database connections, or network connections. Objects that implement IDisposable should have their Dispose() method called when they are no longer needed. In C#, this can be managed automatically using the using statement.

35.What is Reflection in .NET?

Reflection in .NET allows a program to examine its own structure or modify its behavior at runtime. It is used to inspect assemblies, classes, methods, and properties dynamically. Reflection is commonly used in serialization, dependency injection, and building tools like ORMs or test frameworks.

36.What is a Delegate in C#?

A Delegate in C# is a type-safe function pointer that holds references to methods. It allows methods to be passed as parameters, enabling callback functionality or event handling. Delegates are the foundation of anonymous methods, lambda expressions, and events in C#. They promote loosely coupled code by decoupling method invocation from implementation.

37.What is an Event in C#?

An Event in C# is a messaging system that allows objects to notify other objects (subscribers) about changes or actions. Events are built on top of delegates and follow a publish-subscribe model. When an event is raised, all subscribed methods are executed. Events are commonly used for UI actions, like button clicks.

38.What is ADO.NET?

ADO.NET is a set of classes in .NET used for interacting with databases. It allows developers to connect to databases, execute SQL commands, and retrieve data using objects like Connection, Command, DataReader, and DataSet. ADO.NET supports both connected and disconnected data architectures and is widely used for data access in .NET applications.

39.What is MVC in ASP.NET?

MVC (Model-View-Controller) is an architectural pattern used in ASP.NET to create web applications. It divides the application into three components:

• Model: Represents the data.
• View: Renders the UI.
• Controller: Handles user input and updates the model and view accordingly. This separation enhances modularity, testability, and maintainability.

40.What is OAuth in .NET?

OAuth is an open-standard authorization protocol that allows users to grant third-party applications limited access to their resources without sharing their credentials. In .NET, OAuth is used to secure APIs and enable single sign-on (SSO) by integrating with services like Google, Facebook, or Microsoft for authentication.

41.What is SignalR in .NET?

SignalR is a library in .NET that enables real-time web functionality. It allows the server to push asynchronous updates to the client over WebSockets, Long Polling, or Server-Sent Events. SignalR is commonly used for building applications like chat applications, live dashboards, and real-time notifications.

42.What are Web Services in .NET?

Web Services in .NET are standardized ways for applications to communicate with each other over the internet using protocols like SOAP or REST. They enable interoperability between applications running on different platforms. In .NET, WCF (Windows Communication Foundation) and ASP.NET Web API are used to create and consume web services.

43.What is Microservices Architecture in .NET?

A Microservices Architecture is a design pattern where a large application is divided into small, loosely coupled services, each performing a specific function. In .NET, ASP.NET Core is often used to build microservices. Each microservice can be independently developed, deployed, and scaled, making the architecture ideal for cloud-based applications.

44.What is JWT (JSON Web Token)?

JWT (JSON Web Token) is a compact, self-contained way of securely transmitting information between parties as a JSON object. It is commonly used for authentication and authorization in ASP.NET Core applications. A JWT contains a header, payload, and signature and is used in token-based security mechanisms for APIs and microservices.

45.What is the role of the Global.asax file in ASP.NET?

The Global.asax file in ASP.NET is used to define application-level events like Application_Start, Application_End, Session_Start, and Session_End. These events are triggered by the ASP.NET runtime during the lifecycle of the application. It allows developers to perform initialization tasks, such as caching, logging, and error handling.

46.What is ViewState in ASP.NET?

ViewState is a mechanism in ASP.NET Web Forms to persist the state of a page’s controls across postbacks. It stores data in a hidden input field on the page as a Base64-encoded string, ensuring that control properties retain their values when the page is reloaded. While ViewState simplifies state management, it can increase page size.

47.What is Web.config in ASP.NET?

The Web.config file is an XML-based configuration file used in ASP.NET applications to configure settings like authentication, authorization, session state, custom error pages, and connection strings. Changes to the Web.config file are automatically detected by the application, so there’s no need to restart the application for updates to take effect.

48.What is the difference between WPF and Windows Forms?

WPF (Windows Presentation Foundation) is a modern UI framework for building desktop applications with advanced graphics and data-binding capabilities. It supports a more flexible layout system and is better for high-performance apps. Windows Forms, on the other hand, is an older UI framework focused on simplicity and ease of use but lacks advanced UI features like WPF.

49.What is the role of Filters in ASP.NET MVC?

Filters in ASP.NET MVC are used to perform cross-cutting concerns like authorization, logging, exception handling, and caching. There are different types of filters, including Authorization Filters, Action Filters, Result Filters, and Exception Filters. Filters are executed at various stages of the request pipeline and can be applied globally or to specific actions.

50.What is the difference between REST and SOAP Web Services?

REST (Representational State Transfer) is a lightweight, stateless architecture for building web services that use standard HTTP methods (GET, POST, PUT, DELETE). SOAP (Simple Object Access Protocol) is a more rigid protocol that uses XML and requires predefined messaging patterns. REST is preferred for scalability, while SOAP is more suitable for enterprise-level security and transactional systems.