With many organisations growing their digital infrastructure, .Net developers are high up on the list of company’s hiring priorities. If you are readying yourself for your next .NET developer interview, why not let us help you improve your chances.
This post offers 16 .NET developer questions with sample answers to ensure you the greatest head start in acing your next .NET developer interview.
16 .NET developer interview questions.
What’s the difference between .NET and Laravel?
This is one of the more straightforward .NET interview questions you may be asked. This entry level question will allow you to get into a great conversation about where your interests lie, and how you view the role of a .NET developer. You should welcome this opportunity to discuss your wider knowledge about alternative frameworks such as Laravel, and how they may differ from .NET.
Here are some suggestions about what you may like to include in your response.
Your answer should include:
- Languages (e.g. C# support in .NET versus Laravel’s support for PHP)
- Security
- Processing overheads
- .NET’s integration with Visual Studio
- Third-party libraries
- Open-source community support
What is OOP? How does it relate to the .NET framework?
Your answer should include:
- OOP stands for Object Oriented Programming.
- OOP languages such as Visual Basic.NET, C# and C++ are the core languages supported by .NET Framework.
- OOP allows .NET developers to create classes containing methods, properties, fields, events, and other logical modules.
- OOP lets developers create modular programs, which they can assemble as applications.
- OOPs have four basic features: encapsulation, abstraction, polymorphism, and inheritance.
What is encapsulation?
Your answer should include:
- Encapsulation is one of four basic features of OOP.
- It refers to the inclusion within a program object of methods and data needed for that object to function.
- Encapsulation can be described as the act of “hiding” an object, making it private and protected.
- By using binding code, the internal workings of an object are segregated from the rest of the application making it less that other objects can modify the state or behaviour of the object in question.
Explain the concept of inheritance, and how it works in .NET.
Your answer should include:
- In general OOP terms, inheritance means that one class can be based on another class. The child class takes on attributes from the parent class. For example, a .NET dev can code a parent class called “vehicle”, and then child classes which inherit the attributes of Vehicle, possibly called “motorbike”, “car”, “truck”.
- To demonstrate an understanding of this concept, you may like to bring up how .NET supports single inheritance only, meaning that one class can only inherit from one other class.
- Your answer may also veer toward the transitive nature of inheritance, for example the Ford class inherits from Car, which in turn, inherits from Vehicle.
What is the difference between an interface and an abstract class?
Your answer should include:
- An abstract class is always used as a base class.
- An abstract class provides some abstract/virtual members that the inheriting entities must implement, as well as a partial implementation for a functionality.
- For extra marks, you may like to mention that this class can also declare fields, and that developers cannot create an object from this class.
- An interface can declare properties, methods, and events only.
- An interface requires the developer to implement all declared members.
- An interface designates a contract/behaviour that implementing classes should have.
What is the difference between a class and an object? How do these terms relate to one another?
Your answer should include:
- A class is a comprehensive data type that is the primary building block, or template, of OOP.
- Class defines attributes and methods of objects and contains an object’s behaviour and data.
- An object represents an instance of class. Objects are a basic unit of a system. They have identity and behaviour as well as attributes.
- The relationship between the two is that a class defines the states and properties that are common to a range of objects.
What is a delegate in .NET?
Your answer should include:
- A delegate is a type that encapsulates a reference to a method.
- Delegate objects can be passed to code which calls the method according to the method signature; the developer doesn’t have to know at compile time which method is being invoked.
- A delegate can contain references to a single method or multiple methods.
- Delegates are like function pointers in C/C++ and are advantageous because they are type-safe.
What is the difference between a stack and a queue?
Your answer should include:
- A stack keeps track of what is executing. It contains stored value types to be accessed and processed as LIFO (Last-In, First-Out), with elements inserted and deleted from the top end.
- A queue lists items on a FIFO (First-In, First-Out) basis in terms of both insertion and deletion. items inserted from the rear end and deleted from the front end of the queue.
This question is testing your basic knowledge of collections. Other examples of collections you may like to mention in your .NET interview are hash tables, bags, dictionaries, and lists.
What is a .NET web service?
Your answer should include:
- Web services are reusable components. They allow developers to publish an application’s function over the internet to make it accessible and to be able to directly interact with other applications and objects online.
- Web services communicate by using standard web protocols and data formats, including HTTP, XML and SOAP to connect across different platforms and programming languages.
- ASP.NET provides a simple way to develop web services.
- The .NET Framework provides built-in classes for building and consuming web services.
When should you use .NET Web Forms instead of ASP.NET MVC?
Your answer should include:
- The .NET Framework has been based on Web Forms to create web services using Microsoft’s existing Visual Studio Tools. It negated the need for devs to learn new scripting languages.
- Some long running systems may still run as Web Forms.
- Web Forms allows developers to create quick and simple applications.
- In contrast, ASP.NET MVC is fast becoming the choice of 2021 developers.
- In your interview, be sure to mention the advantages of the Model-View-Controller (MVC) architectural pattern.
- MVC’s most important feature is that it allows applications to be broken down into discrete models, views, and controllers; they are much easier to test during development.
What is JSON data? What is one way that .NET developers can work with JSON data?
Your answer should include:
- JSON stands for JavaScript Object Notation.
- JSON gives developers a way to organise and store data so it’s easy to access and read.
- Developers rely on JSON because it allows them to manipulate JSON feeds from other sites and to load them more efficiently than via SML/RSS feeds.
- Json.NET provides a way for .NET developers to define classes that parse objects and arrays from JSON text.
- JSON.NET can also be used if you need to serialise value types into JSON text.
What is the difference between Managed and Unmanaged Code?
Your answer should include:
- A demonstration of your understanding of Common Language Runtime (CLR) which is a crucial part of the .NET Framework.
- Code written in C# or Visual Basic .NET will only run in the CLR, which provides functionalities such as garbage collection and memory management.
- The advantage of this is that managed code is platform-independent; it runs in the CLR rather than the operating system of the machine accessing the application.
- Code written in unsupported languages such as Java will produce unmanaged code, meaning that developers can’t rely on the CLR to provide this kind of portability.
- Managed and unmanaged code are interoperable.
- You may like to evidence your understanding by giving some examples of unmanaged code including COM components, ActiveX interfaces and Win32 API functions.
What is LINQ?
Your answer should include:
- LINQ stands for Language-Integrated Query.
- LINQ is a Microsoft programming model and methodology. It offers developers a way to manipulate data using a succinct, expressive syntax.
- It works by instilling Microsoft .NET-based programming languages with the ability to make formal queries.
- LINQ is part of C# and can be imported as a library in other languages.
What is the difference between Read-only Variables and Constants?
Your answer should include:
- Read-only Variables can support reference-type variables, whereas Constants can only hold value-type variables.
- Read-only variables are evaluated at the runtime, whereas Constants are evaluated at the compile time.
What do the terms “Boxing” and “Unboxing” mean?
Your answer should include:
- Boxing is a process that converts a value type to an object type through “boxing” the variable inside an object or interface.
- Boxing was essential in some old Collection types such as ArrayList. It can still be used for accurate conversion of types. For example, from a double to an int.
- Unboxing extracts this value, storing it in a value type.
What are 3 common acronyms used in .NET? What do they stand for?
Questions like this should be easy to answer for a .NET developer. It affords you some flexibility, allowing you to choose the ones you are most familiar with. You may like to use:
- IL – stands for Intermediate Language. IL is an object-oriented programming language that is a partially compiled code. .NET developers will then compile it to native machine code.
- CIL – stands for Common Intermediate Language. It was once known as MSIL (Microsoft Intermediate Language). Another programming language that .NET developers use, it represents the lowest possible level for a language that humans can still read.
- CLI – stands for Common Language Infrastructure. CLI is a compiled code library that Microsoft developed as an open specification. CLI is used for security, versioning, and deployment purposes.
Of course, you may like to refer to earlier questions to help answer this one. LINQ was covered earlier, as was OOP and CLR.
That’s not all.
Technical knowledge is only part of your interview. You should also be prepared to answer questions about your work so far, and how you are able to support your technical know-how with a host of soft skills.
So,
Be prepared to be asked for your .NET portfolio. Make sure you have examples of your work to hand. If they aren’t available, why not take some of your personal projects to allow your prospective employer a first-hand glance at why they should hire you?
You should also be ready to discuss your knowledge of the SDLC methodologies. Employers will want to know how you have interacted with team members on other projects. For example, have you had multitudes of experience working in Agile environments? Or perhaps you can discuss any experience you have had using newer methodologies…DevOps for example.
Your soft skills cannot be underestimated. Be prepared to shout about your ability to collaborate on projects. Perhaps communication is your forte. Both these attributes are invaluable to a developer working as part of a team and across departments. Your ability to explain technical concepts to non-technical colleagues is crucial, as is your ability to support and mentor others especially as we move more toward hybrid and remote working arrangements. Here too, organisation, motivation and time management come into play.
Make a list of your soft skills and think of tangible examples in which they have served you well.
