Are you preparing for .NET interviews? You are at the right place! I have compiled the most frequently asked .NET interview questions and answers in this blog. Whether you are a beginner or an advanced learner, this blog is the best platform to prepare for .NET interviews. By the end of the article, you will gain a comprehensive knowledge of .NET concepts and the confidence to breeze through your interviews.
.NET is a robust framework designed by Microsoft for building desktop and web applications. Statista says the .NET framework was the most popular technology skill in the .NET C# tech stack in 2023.
Undeniably, .NET is a promising career since it offers endless job opportunities to .NET developers across the globe. Top companies hire .NET developers for high-paying salaries. If you prepare well, you can ace your interviews effortlessly. That's why I have given the crucial .NET interview questions and answers in this blog to help you land your dream job.
Table of Contents
Below mentioned are the Top Frequently asked .Net Interview Questions and Answers that will help you to prepare for the .Net interview. Let's have a look at them.
Before jumping into the .NET interview questions, let’s glance at the skills and responsibilities of .NET developers.
In this section, I have outlined the primary and secondary skills required for .NET developers and listed their job responsibilities at various expertise levels.
Let’s check them out!
The following are the essential skills required for .NET developers.
Below are the secondary skills required for .NET developers.
The following are the job responsibilities of entry-level .NET developers.
Below are the job responsibilities of the intermediate-level .NET developers.
The following are the responsibilities of senior-level .NET developers.
Well! I hope you have gained insights into the .NET developer skills and job responsibilities. I am sure that it will help you prepare effectively for your interviews.
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We have categorized Net Interview Questions into 3 levels they are:
Ans: .NET is an open-source application platform on which we can build mobile, web, and desktop applications. The platform consists of many tools, programming languages, and libraries for application development.
.NET is a high-performance, secure, and reliable application platform that supports different operating systems, such as Android, Windows, Linux, and macOS. It has a standard set of libraries and APIs, including machine learning and networking domains. Moreover, .NET has many application models built over the base libraries.
Ans: .NET framework is essentially a software development framework that allows us to build and run applications on Windows. Also, it supports running websites and services on Windows.
The .NET framework components are the class library and the common language runtime. The CLR is the execution engine that controls running applications, while the class library provides a rich set of APIs and types.
Ans: .NET Framework 4.8.1 is the latest version of the .NET framework, released on August 9, 2022.
Ans: The following are the new features of the .NET framework 4.8.1.
Ans: .The .NET framework supports over sixty programming languages, including C#, VB.NET, F#, VC++, Perl, and Python.
Ans: .NET is an open-source platform containing around 32 programming languages and several tools for application creation. It is highly secure and runs comfortably on multiple computer platforms.
Ans:
Ans: Some OOP languages are Java, JavaScript, C#, C++, Python, Visual Basic, Ruby, .NET Typescript, and PHP.
Ans: JIT stands for JustInTime. It is a compiler that converts bytecodes into machine codes quickly. We can use JIT compilers to improve application runtime.
The main thing about the JIT compiler is that it compiles codes after a program starts. In other words, the JIT compiler runs codes on the fly. Java Virtual Machine and Common Language Runtime uses JIT compilers.
Ans: Below are the primary JIT compilers that we can find in the .NET ecosystem.
Ans: OOP is the acronym for Object-Oriented Programming. It is a programming structure that uses self-contained entities called ‘objects’ instead of methods to achieve the desired functionality. OOP allows .NET developers to create modular programs and classes containing methods, properties, fields, events, and other logical modules.
Ans: The basic features of OOP are:
Ans: Simula was the first OOP language and Java, JavaScript, Python, C++, Visual Basic. NET, Ruby, Scala, PHP are few others.
Discover a curated collection of OOP interview questions and comprehensive answers, designed to help you prepare thoroughly for your next technical interview. |
Ans: JIT stands for Just In Time. It is a compiler in CLR responsible for the execution of .NET programs of different languages by converting them into machine code. It speeds up the code execution and supports multiple platforms.
Ans: There are 3 types of JIT Compilers:
i. Pre-JIT compiler: It compiles all the source code into the machine code in a single compilation cycle, i.e. at the application deployment time.
ii. Normal JIT Compiler: The source code methods required at run-time are compiled into machine code and stored in the cache to be called later.
iii. Econo JIT Compiler: The methods required only at run-time are compiled using this compiler and they are not stored for future use.
Ans: BCL stands for Base Class Library. It comprises classes, interface, and value types. It is the foundation for building .NET Framework applications, components, and controls.
Ans: FCL stands for Framework Class Library and is a collection of reusable types, including classes, interfaces, and data types included in the .NET Framework. It is used for developing a wide variety of applications, as it provides access to system functionality.
Ans: Caching is a method of storing data in an intermediate layer. It allows quick access to data and improves data availability. Caching in .NET supports improving application performance. The main thing about caching is that we can access data even if the data source is temporarily unavailable.
.NET provides two types of MemoryCache classes. One class is the System.Runtime.Caching namespace, and another class is Microsoft.Extensions.Caching namespace.
Ans: There are 3 types of caches in .NET:
Ans: .NET is an OOP framework since it broadly supports encapsulation and inheritance.
Ans: Yes, .NET supports multithreading. It is done in two ways, as mentioned below.
Ans: WCF is a framework that we use to build service-oriented applications. It supports sending asynchronous messages from one service end to another. The messages can be a single character, word, or complex binary data. The service end can be a service hosted by IIS or an application. In short, WCF simplifies creating web services and web service clients.
WCF follows the latest industry standards for web service interoperability. It follows multiple message patterns such as request/reply, one-way message, and duplex exchange patterns.
Ans: SOA is a software development method using software components to build applications. The software components are called services. Each service provides a business capability. The services can interact with each other. We can reuse services in different systems. Similarly, we can combine different independent services to perform complex tasks.
For example, we can use SOA in the user authentication process. An organisation's various processes may require user authentication. We can develop and reuse a single authentication service for multiple business processes with SOA.
Ans: Agile is a project management methodology in which a project we can divide a project into multiple phases. The core of the agile methodology is collaboration and continuous improvement. The methodology follows a cycle of planning, executing, and evaluating.
Agile project management is essentially an iterative approach. It simplifies software development projects that involve continuous releases and incorporates customer feedback into every iteration.
Ans: TDD methodology emphasises writing test cases before developing an application function or feature. It follows the iterative development cycle with short intervals. Simply put, TDD performs development and testing back-to-back.
TDD follows the below cycle in product development.
Ans: There are five steps in the ORM process. They are:
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The constructor in C# is a unique class method with a collection of instructions. When a class instance is created, a constructor is invoked automatically.
Ans: EXE is an executable file that works as an application and it runs individually as it contains an entry point. DLL is a Dynamic Link Library which is a supportive file to other applications, and it cannot run individually.
Ans: System.String is immutable and fixed-length, whereas Systems.StringBuilder is mutable and variable-length. We can change the size of the .string, but we cannot change the size of the .stringbuilder.
Ans: There are four pillars in OOP. Let’s take a look at them below.
In this section, I have included the advanced .NET interview questions to help you crack tough .NET interviews effortlessly.
Let’s go through them!
Ans: Cross-page posting supports posting form data from one page to another. It helps avoid the overhead of reloading the current page. We use the PostBackURL attribute to specify the page we want to post.
ASP.NET page posts back to itself to process events. For example, once we have entered data on an ASP.NET page, we will hit the submit button. After saving the data, the page posts back to itself.
Ans:
Read-only Variables | Constants |
It is a run-time constant. | It is a compile-time constant. |
We store read-only variables in the memory heap. | We store const variables in metadata. |
We use the read-only keyword to create read-only fields. | We use the const keyword to build constant fields. |
Ans: A value type is stored in a stack, but at the same time, the reference type is stored in a heap.
A value type stores data in its memory location, whereas a reference type points to another memory location where data is stored. Value types are passed by value, so a copy of data is created when assigned to a variable. Reference types are passed by reference, so the reference to data is used when assigned to a variable.
Ans: We use a stack to store temporary variables. Stack memory stores data based on a linear data structure. We use Stack memory for static memory allocation.
On the other hand, we use a heap for dynamic memory allocation. Accessing data in a heap memory is a slow process. Heap stores data using the hierarchical structure. This means that data is stored in a heap in a tree form.
Ans:
Stack | Queue |
It follows the LIFO principle | It follows the FIFO principle |
It allows inserting and deleting elements from the top end. | It enables inserting elements from the rear end and their deletion from the front end. |
The last inserted data is processed first | The first entered data is processed first |
A stack uses a single pointer on the top end. | A stack uses two pointers. One at the front end and another at the rear end. |
Ans: BCL is the Base Class Library with interfaces, classes, and value types. This library helps to build .NET framework components, applications, and controls.
FCL is the Framework Class Library, a collection of reusable types. This library includes the interfaces, classes, and data types of the .NET framework. It provides access to system functionality, which is why we can use it to develop different applications.
Ans: An EXE file is an executable file used to run applications. It contains application codes, resources, and dependencies. EXE files are also standalone files directly executed by users.
A DLL file is basically a dynamic link library that stores reusable codes. These files contain codes we can share with other programs and provide common functionality that multiple programs can use.
Ans: .NET follows the SOLID design principles, as listed below.
Ans: The For loop provides a concise way of writing the loop structure, but the While loop is a control flow statement that allows repetitive execution of the code. Initialization, condition checking, iteration statements are written at the top of the For loop, but only initialization and condition checking is done at the top of the while loop.
Syntax:
While loop:
while(condtion) {
//statements to excute.
}
For loop:
for(intialization; condition; Increment or decrement){
// statements to be excuted.
}
Ans: The base class is a class whose members and functions can be inherited, and the derived class is the class that inherits those members and may also have additional properties.
Ans: The extension method is used to add new methods in the existing class or the structure without modifying the source code of the original type. Special permission from the original type or re-compiling it isn’t required.
Ans: Inheritance is one of the basic properties of OOP. It allows a child class to inherit the behaviour of its parent class. In other words, inheritance is a method of creating hierarchies of objects. Here, one class in a hierarchy depends on another class.
Ans: Inheritance hierarchy is a singly rooted tree structure for organizing classes.
Ans: When it comes to implementation inheritance, a class inherits all its members from the same source. When it comes to interface inheritance, a class inherits only the functions' signatures from another class.
Ans: To prevent a class from being inherited, the sealed keyword in C# can be used. The NotInheritable keyword can be used in VB.NET to prevent accidental inheritance of the class.
Ans: A constructor is a special method of the class that contains a collection of instructions and gets automatically invoked when an instance of the class is created.
Ans: There are 5 types of constructors in C#, as given below:
Ans: Method Overriding is a process that allows using the same name, return type, argument, and invoking the same functions from another class (base class) in the derived class.
Ans: Shadowing makes the method of the parent class available to the child class without using the override keyword. It is also known as Method Hiding.
Ans: Shadowing is used to provide a new implementation for the base class method. It helps protect against subsequent base class modification.
On the other side, Overriding allows rewriting a base class function with a different definition and achieves polymorphism.
Ans: Polymorphism refers to one interface with multiple functions. It means that the same method or property can perform different actions depending on the run-time type of the instance that invokes it.
Ans: There are two types of Polymorphism:
i. Static or compile-time polymorphism
ii. Dynamic or runtime polymorphism
Ans: No, .NET supports only single inheritance. In .NET, a class can inherit only from a single class.
Ans: The diamond of death problem occurs when classes A and B inherit from one base class A. Classes A& B inherit a class known as class D. If a method in class A, Classes B, and C have overridden the method, class D may not override the method. Now, which method class D inherits is a question mark. It is known as the diamond of death.
Ans: An interface is a declaration for a set of class members. It is a reference type that contains only abstract members such as Events, Methods, Properties, etc.
Ans: Events are stored as public class members. On the other hand, delegates are stored as private class members. Delegates are also passed as parameters.
Ans: It is the application processing layer that coordinates between the User Interface Layer and Data Access Layer.
Ans: We can place a control inside the form area and a component below it. Know that all controls can be components, but not all components can be controlled. A component cannot draw itself on a form; a control handles the drawing process.
Ans: A single application can use custom controls, while many can use user controls.
Ans: Functional requirements are the basic and mandatory facilities that must be incorporated into a system. Non-functional requirements are quality-related attributes that the system must deliver.
Ans: We use reflection objects to create type instances. They also help obtain type information at runtime and support implementing late binding. They use the PE file to read the metadata of an assembly. The classes of System.Reflection namespace supports accessing the metadata of a running program.
We use .NET reflection to find all types in an assembly. It also helps invoke methods dynamically in an assembly and includes information about objects' types, methods, properties, and events.
Ans: GAC is a machine-wide code cache stored in the Common Language Runtime. The GAC stores .NET assemblies that many applications will share. The main thing is that we can share assemblies by installing them in the GAC cache.
We can deploy an assembly in GAC using two methods. In the first method, GAC uses an installer. Another method uses a developer tool known as the GAC tool.
Ans: Object-Role Modeling (ORM) is a powerful method for designing and querying information systems at the conceptual level. It is an easy and understandable description of the application for non-technical users.
Ans: Globalization is designing and coding culture-neutral and language-neutral applications. Localization is customizing the application and translating the UI based on specific cultures and regions.
Ans: MIME stands for Multipurpose Internet Mail Extension. It is a supplementary protocol that sends non-ASCII data through SMTP and facilitates the exchange of data files on the Internet..
Ans: The Hashtable class is basically a collection. It stores key-value pairs and organises them based on each key's hash code, which is used to access elements in the collection.
Well! You have gone through the key .NET interview questions, which must have given a strong foundation on .NET concepts.
Ans: The following are the different design patterns of the .NET framework.
i. Factory Method
ii. Abstract Factory
iii. Builder
iv. Prototype
v. Singleton
i. Adapter
ii. Bridge
iii. Composite
iv. Decorator
v. Façade
vi. Flyweight
vii. Proxy
i. Chain of Responsibility
ii. Command
iii. Interpreter
iv. Iterator
v. Mediator
vi. Memento
vii. Observer
viii. State
ix. Strategy
x. Visitor
xi. Template Method
In this section, I have included the crucial .NET interview questions and answers to improve your expertise in the .NET platform.
Let's jump in!
Ans: Marshalling is the critical process of transforming types in the managed and unmanaged code.
Ans: Boxing and Unboxing enable a unified view of the type system to treat the value of any type as an object.
Ans: Both Server.Transfer and Response.Redirect is used to redirect a user from one web page to another. The Response.Redirect method requests a new URL and specifies the new URL.
The Server.Transfer method terminates the execution of the current page and starts the execution of a new page.
Ans: The garbage collector in .NET manages the allocation and release of memory for applications. Its optimising engine looks for the best time and removes objects in heap memory that are no longer used by applications.
Furthermore, the garbage collector in .NET supports automatic memory management, so developers don’t need to write codes for memory management tasks. Automatic memory management helps avoid memory leaks by optimising memory management.
Ans: The memory heap is divided into three generations.
Ans: A call to the Debug class is included in Debug mode only. It is used during the application development.
On the other hand, a call to the Trace class can be included in Debug and Release mode. It is used during the application deployment.
Ans: Debug builds don’t allow the accurate setting of breakpoints. They contain debugging symbols. The code built-in "Release" build is optimised for speed or size without any debug data.
Ans: An application object shares information with all application users. We can put together a set of ASP files to perform a specific purpose.
Ans: A Session object stores information and variables. It retains them throughout the session.
Ans:
Managed Codes | Unmanaged Codes |
They run inside a runtime environment. | They run directly on hardware. |
We need to install the .NET framework for execution. | We don’t need to install the .NET framework for execution. |
They provide automatic memory management. | It needs manual memory and pointers management. |
It provides security to applications. | It doesn't provide security to applications. |
It doesn’t allow a memory buffer overflow | It will enable memory buffer overflow. |
Ans: The steps for executing a managed code are as follows:
Ans: The different parts of an Assembly are:
Ans: MVC stands for Model View Controller. It is an architectural model that helps create .NET applications. Besides, MVC is an easy-to-use architecture that supports controlling HTML.
Ans: Stored Procedures are pre-compiled objects that execute the code when called for. On the other hand, the Function is compiled and executed when it is called for..
Ans: We can locate a web service in .NET on a web server. A .NET web service uses standard web protocols to interact with other network applications. The protocols can be HTTP and SOAP. A web service that performs asynchronous communications for XML applications. The applications operate over a .NET communications framework.
Also, the .NET web service is a component that helps publish an application's function on the web, making it available to the public.
Ans: The advantages of Web Services are:
Ans: MEF is the short form of the Managed Extensibility Framework. It is a library that enables the host application to consume external extensions without configuration.
Ans: A tuple is essentially a data structure. It contains a sequence of elements of different data types. Tuples are data structures that support holding object properties. They avoid creating separate types to hold object properties.
The code below helps create a tuple with three elements.
Tuple<int, string, string> person =
new Tuple <int, string, string>(1, "Joe", "Jobs");
Ans: ADO is the short form of ActiveX Data Objects. It is an application program that supports writing Windows applications. It is used to access a relational or non-relational database from different providers.
Ans: There are two fundamental objects in ADO.NET:
Ans: Object pooling allows using limited resources with the help of software constructs. We can store objects, ready-to-use connections, and threads in a pool in memory so we can use them as and when required. We can pull a new object from the pool and allocate it for a request. Overall, pooling improves performance and scalability.
Ans: Client-side validations occur at the client’s end. JavaScript and VBScript languages are used for the validations since they enhance user experience. Also, the inputs for the client-side validations occur in users’ browsers.
On the other hand, server-side validations occur on the client’s end. ASP.net and PHP languages are used for server-side validations. We can send feedback through a dynamically generated new webpage.
Ans: Serialisation is typically the process of converting the state of an object into a form. We can transport the form.
Deserialisation converts a stream into an object. It allows data to be stored and transferred.
Ans: PE stands for Portable Executable. It is a derivative of the Microsoft Common Object File Format (COFF). Windows executable. EXE or DLL files follow the PE file format. It consists of four parts:
Ans: .EXE files are single outbound files that cannot be shared with other applications. DLL files are multiple inbound files that are shareable.
Ans: DataSet.Clone copies only the structure of the DataSet, including all DataTable relations, schemas, and constraints. It does not copy any data.
DataSet.Copy is a deep copy of a DataSet. It duplicates both its structure and data.
Ans: The Errorprovider is a simple mechanism that indicates to end-users that a control on a form has an error. If an error description control is specified, then an icon comes up next to the control.
Ans: A thread is a small set of instructions. We use a thread class to create and manipulate a thread in Windows. On the other hand, a task is an object that represents a work, and it returns a result. It also represents an asynchronous operation.
We can cancel a task using the cancellation tokens, whereas threads don’t allow cancellation. A task can run multiple processes simultaneously, whereas a thread can only have one task simultaneously.
Ans: NET is an OOP framework as Encapsulation and Inheritance are key features of the Object-Oriented Programming framework.
Ans: Multithreading is a process of performing multiple activities in a single process. .NET supports multithreading in two-way.
Yes, .NET is easy to learn. If you devote your time and energy, you will learn .NET quickly. MindMajix offers advanced .NET training with highly skilled trainers. The training is offered providing maximum importance to practicals. Once you complete training from MindMajix, you will step out as a competent .NET developer and excel in your career.
According to Zippia, Fortune 500 companies hire .NET developers in large numbers. Finance and technology companies also hire .NET developers. According to Glassdoor, Infosys, Wipro, TCS, and HCLTech companies hire .NET developers with attractive salary packages. The average salary of .NET developers is 6 LPA in India. In the USA, the average salary for a .NET developer is 133k USD per year. So, the .NET developer job is in demand and rewarding.
MindMajix offers .NET training in two modes: live online and self-paced videos. Each mode contains 50 hours of training, including classroom and lab sessions. If you prefer live online training, you will complete it within 15 days. If you choose self-paced video-based training and watch three videos per day, you will complete it within 17 days.
No, AI won't replace .NET developers in the current chatGPT evolution scenario. AI can simplify their tasks but cannot replace them. AI can help with optimisation, code generation, and bug detection. However, it is challenging for AI to understand human context, perform debugging, ensure ethical and legal compliance, etc.
If you want to become a competent Windows application developer, gain expertise in C#.NET technology. If you want to become a skilled web application developer, gain expertise in ASP.NET technology and ASP.NET MVC. If you want to become a high-quality mobile application developer, gain expertise in Xamarin. In addition to the above, you must acquire proficiency in crucial technologies like HTML, Javascript, CSS, GitHub, etc.
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Ravindra Savaram is a Technical Lead at Mindmajix.com. His passion lies in writing articles on the most popular IT platforms including Machine learning, DevOps, Data Science, Artificial Intelligence, RPA, Deep Learning, and so on. You can stay up to date on all these technologies by following him on LinkedIn and Twitter.