ASP.NET is a powerful framework for building dynamic web applications, known for its scalability, performance, and integration with the .NET ecosystem, developed by Microsoft that allows developers to build dynamic web applications, websites, and services. It is part of the larger .NET framework and provides a comprehensive programming model for creating web applications with features like server-side code execution, rich user interface controls, and seamless integration with other Microsoft technologies. ASP.NET is widely used in top companies such as Microsoft, Dell, Stack Overflow, TCS, Accenture, and many more because of its robust features and ability to support enterprise-level applications. powers an overload of websites and web applications across various domains, making it a top choice for developers worldwide.
In this article, we will provide Top ASP.NET Interview Questions tailored for both freshers and experienced professionals with 3, 5, and 8 years of experience. Here, we cover everything, including core ASP.NET concepts, MVC architecture, Web API, Razor pages, security, state management, performance optimization, and more, that will surely help you to crack ASP.NET interviews.
ASP.NET (Active Server Pages . NET) is a progressive new programming framework that empowers the rapid improvement of powerful web applications and administrations. It is a part of the Microsoft .NET Platform, it gives the simplest and most versatile approach to creating, deploying and running web applications that can focus on any browser or device.ASP.NET is built on the CLR(Common Language Runtime) which allows the programmers to execute its code using any .NET language(C#, VB, etc.). It is specially designed to work with HTTP and for web developers to create dynamic web pages, web applications, websites, and web services as it provides a good integration of HTML, CSS, and JavaScript.
.NET Framework is used to create a variety of applications and services like Console, Web, and Windows, etc. But ASP.NET is only used to create web applications and web services. That’s why we termed ASP.NET as a subset of the .NET Framework.
There are a lot of reasons which make ASP.NET popular among developers. Some reasons are listed below:
CLR is the basic and Virtual Machine component of the .NET Framework. It is the run-time environment in the .NET Framework that runs the codes and helps in making the development process easier by providing various services such as remoting, thread management, type-safety, memory management, robustness, etc. Basically, it is responsible for managing the execution of .NET programs regardless of any .NET programming language. It also helps in the management of code, as code that targets the runtime is known as the Managed Code, and code that doesn’t target to runtime is known as Unmanaged code.
ASP.MVC is a web application framework that is lightweight and has high testable features. ASP.NET supports 3 different types of components namely Model, View, and Controller.
ASP.NET has Server Controls features, Which provide facilities to manipulated values of the controls on the Server-Side. This is especially helpful while we want to create validating and dynamically web forms.
A configuration file (web.config) is utilized to oversee different settings that characterize a website. The settings are store in XML files that are independent of your application code. In this manner, you can configure settings freely from your code. This file stored inside the application root directory.
To complied an ASP.NET program .NET framework used the Roslyn compiler.
ASP.NET is an open-source web framework for building web applications on the .NET (dotNET) framework. It is made by Microsoft and variant 1.0 was delivered in 2002 to allow users to develop dynamic web applications, services, and sites. The framework is designed to work with the standard HTTP convention, which is the standard protocol utilized across all web-based applications. ASP.NET is the replacement to the ASP (Active Server Pages) innovation and was a significant update as far as adaptability and power. It is an expansion of the .NET framework with extra tools and libraries for building things on the web, including web applications and websites. The ASP.NET cross-plate form version is known as ASP.NET Core, which was delivered in 2016. ASP.NET is still updated and supported.
Global.asax is an optional file that resides in the application root directory. This file is used to handle higher-level application events, for example, Application_Start, Application_End, Session_Start, Session_End, and so on. It is additionally known as the ASP.NET Application File..Global.asax contains a Class representing your application as a whole. At run time, this file is parsed and compiled into a dynamically created .NET Framework class derived from the HTTP Application base class. We can convey this file as an assembly in the \bin catalog of an ASP.NET application. The Global.asax record itself is designed so that if a user demands the document, the request is denied. External users can’t download or see the code written inside it.
There are mainly four different types of Server-side controls in ASP.NET :
A PostBack is the process of presenting an ASP.NET page to the server for processing. PostBack is done if certain credentials of the page are to be checked against certain sources, (for example, confirmation of username and secret key/password using a database). This is something that a client machine can not able to achieve and subsequently, these details must be ‘posted back’ on the server. So we can say that a postback event occurs on the client-side but is handled by the code in a copy of the page running on the server.
There is some key difference between Web.config and Machine.config file below:
Grid View
DataGrid
It was introduced with Asp.Net 2.0.
It was introduced with Asp.Net 1.0.
Built-in supports for Paging and Sorting.
For sorting you need to handle SortCommand event and rebind grid required and for paging, you need to handle the PageIndexChanged event and rebind grid required.,
Built-in supports for Update and Delete operations.
Need to write code for implementing Update and Delete operations.
Supports auto-format or style features.
This feature is not supported.
Performance is slow as compared to DataGrid
Performance is fast as compared to GridView.
User Control
Custom Control
User controls are created just like a web form. They make use of the existing controls to define their own logic.
A custom control is one that is made or created by the programmer to serve the business needs, by extending the functionality of existing controls.
We can User control easily.
The creation of custom control is not easy as compare to user control
These control do not run on their own dll.
While these control can run on their own dl.
We can not add to the toolbox.
While we can add to the toolbox.we
This control is not flexible.
This control is more flexible.
Once we created a single copy of this control, we can use this copy to different projects as well.
We can not call or use a single copy of this control in different applications. For this, we need to create a control for each and every application.
Web server controls are powerful than HTML server-side controls. The only difference is that they must have the runat = ”server” attribute set. This attribute makes the control available for server-side programming. Each ASP.NET Server Control is capable of exposing an object model containing properties, methods, and events. This object model can be utilized by the ASP.NET developers to modify and interact with the Web page. Web controls contain all basic controls of HTML controls as well as some new controls like as DataGrid, DataList, and Calendar.
WEB CONTROL
DESCRIPTION
Represents a label control
Represents a list box control
Represents a Check box control
Represents a calendar control
Represents an image button control
Represents a table cell
Represents a panel control
Represents a data list control
Represents a text box control
Represents an image control
Represents a list box with checkboxes
Represents a button control
Represents a hyperlink control
Represents a row of a table
Represents a list box with radio button controls
Represents a data grid control
Represents a drop-down list control
Represents an ad rotator control
Represents a radio button control
Represents a link button control
Represents a table control
Represents a repeater control
The ASP.NET supports robust login controls for web-based application which does not require any program coding. These login controls coordinate with ASP.NET participation and form authentication to help automated client verification for a server webpage. By default, the ASP.NET login controls work in plain text over HTTP. The ASP.NET supports different types of Login Controls like:
Validation controls in ASP.NET are one of the significant requirements for Web application creation. These controls give the facility to validate user input. By using these controls we can check as a required field, range, custom rules, conditions, etc. An asp.net has 5 different types of validation controls:
This control creates a check box on a Web Forms page, allowing users to set a true or false value for the item associated with the control. The properties of the CheckBox are:
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#form1 <>
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OnClick="Button1_Click" Text="Submit " />
Text="Label">
Output 1:
Output 2:
HTML Server Controls : HTML elements are exposed to the server. They expose an object model that maps very closely to the HTML elements that they render. You can run these controls on the server by defining the runat =”server” attribute.
| CONTROL | DESCRIPTION |
|---|---|
| HtmlForm | Create an HTML form control, used as a placeholder for other controls. |
| HtmlInputText | Creates an input text box control used to get input from the user. |
| HtmltextArea | Creates multi-line text box control. |
| HtmlAnchor | Creates Web navigation. |
| HtmlButton | Creates a button control. |
| HtmlImage | Creates an image control, which is used to display an image. |
| HtmlInputCheckBox | Creates a checkbox control. |
| HtmlInputRadioButton | Creates a radio button control. |
| HtmlTable | Creates a table control. |
| HtmlTableRow | Creates a row within a table. |
| HtmlTableCell | Creates a cell within a row. |
LINQ is known as Language Integrated Query and it is introduced in .NET 3.5 and Visual Studio 2008. The beauty of LINQ is it provides the ability to .NET languages(like C#, VB.NET, etc.) to generate queries to retrieve data from the data source. For example, a program may get information from the student records or accessing employee records, etc. In, past years, such type of data is stored in a separate database from the application, and you need to learn different types of query language to access such types of data like SQL, XML, etc. And also you cannot create a query using C# language or any other .NET language.
To overcome such types of problems Microsoft developed LINQ. It attaches one, more power to the C# or .NET languages to generate a query for any LINQ compatible data source. And the best part is the syntax used to create a query is the same no matter which type of data source is used means the syntax of creating query data in a relational database is the same as that used to create query data stored in an array there is no need to use SQL or any other non-.NET language mechanism. You can also use LINQ with SQL, with XML files, with ADO.NET, with web services, and with any other database.
ASP.NET Core is the open-source version of ASP.NET, that can be run on macOS, Linux, and Windows. ASP.NET Core was first delivered in 2016 and is a re-plan of prior Windows-just forms of ASP.NET.
In November 2015, Microsoft released the 5.0 version of ASP.NET which get separated later and known as ASP.NET Core. Also, it is considered as an important redesign of ASP.NET with the feature of open-source and cross-platform. Before this version, ASP.NET is only considered a Windows-only version.
In ASP.NET, Razor provides the syntax for developing dynamic web pages with the help of C# and HTML. ASP.NET can be integrated with JS(JavaScript) and it also includes the frameworks like React and Angular for the SPA(Single Page Application).
Authentication is the process of checking the identity of a user based on the user’s credentials. Generally, user’s credentials are in the form of user ID and password, and we check their credentials from a database or equivalent alternative if it exists then the user is a valid candidate for the next process – authorization. There are different types of Authentication available in ASP.NET namely:
A QueryString is a collection of characters input to a computer web browser. It is helpful when we want to transfer a value from one page to another page. If the sending data is in large quantity then we can not use Request.QueryString because it supports only 255 characters. We use the ‘&’ special character for separate multiple query strings. Any query string that was available to the calling ASPX page will be available to the called ASPX page.
A web application is a piece of software that can be accessed by the browser. A Browser is an application that is used to browse the internet. Web application needs authentication. The web application uses a combination of server-side scripts and client-side scripts to present information. It requires a server to manage requests from the users. For example, Google Apps
A website is a collection of related web pages that contains images, text, audio, video, etc. It can be consist of one page, two pages, and n number of pages. A website provides visual and text content that users can view and read. To view a website requires a browser(chrome, firefox). There are many types of websites like Archive website, Blog, Community website, Dating website, etc. For example, Amazon, youtube, etc.
View state is the method that the ASP . NET page framework uses to preserve page and control values between round trips.
Inherits="WebApplication9.WebForm4" %>
Example of View State:
WELCOME TO GEEKSFORGEEKS
Page Counter:
Text="Number of Visitors Count" OnClientClick="btnIncrement_Click" />
Output:
A Cookie can be defined as small pieces of information, which can be sent to a browser by a server program and stored by the internet browser. The internet browser will then, at that point pass the Cookies back to the server each time it makes a request from that server. This is especially helpful for permitting verification/ authentication.
Suppose, when a user signs in to a password-restricted system, a cookie stores user information (user name, password). So the client doesn’t need to re-type their details information for each new page they wish to download. The cookie property gets a collection of the client’s cookie variables.
Web services are a web application that is fundamentally a class comprising of methods that could be utilized by different applications. It likewise follows a code-behind design, for example, the ASP.NET pages, despite the fact that it doesn’t have a user interface.
The sequence for Request Flow in ASP.NET MVC is as follows:
We can maintain sessions in MVC using three different ways:
Repeater control is derived from the Control class. A repeater simply repeats data given in templates. Repeated data is usually HTML code mixed with records from the data sources. Repeater’s output is not predefined. Because of that, Repeater demands most work to define the template. In return, it gives us the most flexibility to build the layout and optimize the presentation.
With the same template and same data set, Repeater usually works faster than Data List or GridView controls. This is mostly because of the DataReader class, which is used for read-only access. DataReader is faster than DataSet or DataTable classes commonly used with GridView.
Compared to GridView and DataList control, Repeater has limited features. By default, Repeater is good for displaying data. It is not the best choice if you need editing of data. Also, by default, it doesn’t provide paging and sorting of records.
ListView control is the newest data presentation control, introduced in ASP.NET 3.5. Previous controls (Repeater, DataList, and GridView) logically follow each other. For example, Repeater is simplest but fastest, then DataList has more features but more overheads too, and finally GridView is most complex, has most features, but heaviest and thus slowest on-page. Now, there is new ListView control that tries to provide the best from both sides: speed and flexibility in design, and also a lot of features like paging, updating or deleting of records, etc. Because of this, ListView control is often a better choice than Repeater or DataList.
The ASP.NET supports a robust login controls for web-based application which does not require any program coding. The LoginStatus control is a very simple control, all it does is display a link that is different depending on whether the user is logged in or logged out. If a user is logged in then it displays a LogOut link and vice versa.
There are few properties that it supports, LogOutAction can be used to specify what happens when a user clicks on the LogOutLink, and the options are Redirect, RedirctToLoginPage, Refresh. If we set it to Redirect then we must set another property LogOutPage Url which a user is redirected to after logging out of the website.
CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication10.WebForm1" %>
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ForeColor="#CC0000" LoginText="Click here for Login" />
ForeColor="#CC0000" LoginText="Click here to Logout" />
Just-In-Time(JIT) Compiler: Just-In-Time compiler(JIT) is a part of Common Language Runtime (CLR) in .NET which is responsible for managing the execution of .NET programs regardless of any .NET programming language. A language-specific compiler converts the source code to the intermediate language. This intermediate language is then converted into the machine code by the Just-In-Time (JIT) compiler. This machine code is specific to the computer environment that the JIT compiler runs on.
The RedirectPermanent(String) method overload gives a 301 HTTP status code in the reaction and incorporates the URL to divert the request. A 301 HTTP status code is a standard code in an HTTP reaction. It shows that a lasting redirection exists, and it gives the redirection area.
The full form of ASP.NET AJAX is Asynchronous JavaScript and XML. ASP.NET AJAX also known as AJAX, is a bunch of augmentations of ASP.NET. It uses asynchronous data transfer between browser and webserver to allow web pages to request small bits of information from the server instead of entire pages. This technique makes Internet applications smaller, faster, and more user-friendly. It is created by Microsoft to execute AJAX functionalities in Web applications. The ASP.NET AJAX works with the AJAX Library that utilization object-arranged programming (OOP) to faster rich Web applications.
At the point when server-side processing is included, then there are four stages included:
Now, stage 3 is known as a page postback, while stages 3 and 4 are aggregately known as a “roundtrip”. We can say that- “A roundtrip includes making a total excursion over the network to the Web browser and getting the reaction back. The Web applications use HTTP to build up correspondence between the Web program and the Web server.
REST stands for RE presentational S tate T ransfer.REST is an architectural style that doesn’t follow any strict standard but follows six constraints defined by Roy Fielding in 2000. Those constraints are – Uniform Interface, Client-Server, Stateless, Cacheable, Layered System, Code on Demand.REST is not restricted to XML and it’s the choice of implementer which Media-Type to use like XML, JSON, Plain-text. Moreover, REST can use SOAP protocol but SOAP cannot use REST.REST is easy to implement and requires less bandwidth such as smartphones.
Architectural Constraints of RESTful API: There are six architectural constraints that make any web service are listed below:
In Asp.Net the caching method allows to store or cache Web Page output. This technic is used to avoiding the overhead of recreating the same data. There are three different caching types available in ASP.NET:
Caching increases the performance parameter if the same data or information is requested by the user.
The Finalize technique is utilized to perform a cleanup procedure on unmanaged resources held by the current object before the object is destroyed. The strategy is ensured and subsequently is available just through this class or through a derived class.
ASP.NET includes an easy-to-use functionality that helps to debug Web applications. Tracing functionality allows debugging print statements to be inserted into the code to output variables or structures, assert whether a condition is met, or trace through the execution path of the application. Trace feature is used to track particular types of actions in a deployed application as they occur (for example, database connections), and can thus monitor the application’s efficiency. The new tracing features of ASP.NET allow simulating Response.Write() statements. The users need not worry about removing the statements before deploying the applications. Instead of using Response.Write(), Trace.Write() is used. The Trace object is an intrinsic page object, similar to Request, Response, Server, etc. It is accessible directly with the page code.
Trace class: A Trace class is used to get information about Trace. When the Trace property is used, an instance of the TraceContext class is defined in the System.Web namespace. Trace class provides a set of methods and properties that help to trace the execution of code. Instrumentation allows monitoring the health of the application running in real-life settings. Tracing helps to isolate problems and fix them without disturbing a running system.
There are two different ways to enable tracing:
A local resource is explicit to a specific page, which is the one in particular who can get to it, while global resources can be accessed from any place. Local resources are kept in the App_LocalResources organizer, while global are kept in the App_GlobalResources folder. Local and global resources records will appear to be identical, so the only distinction is the folder they reside in. But they are utilized in different.
Navigation Control is defined as a menu that can be stored in a file to make it easier to maintain. This file is normally called web.Sitemap, and is stored in the root directory of the web. An ASP.NET has three different types of Navigation control:
The TreeView control is made up of nodes. Each entry in the tree is called a node and is represented by a TreeNode object. A node that contains other nodes is called a parent node. A node that is contained by another node is called a child node. A node that has no child nodes is called a leaf node. A node that is not contained by any other node but is the ancestor to all the other nodes in the root node. A node can be both a parent and a child, but root, parent, and leaf nodes are mutually exclusive. Several visual and behavioural properties of nodes are determined by whether a node is a root, parent, or leaf node.
ASP.NET has introduced the next generation of ADO known as ADO.NET with respect to data access. ADO.NET places more emphasis on disconnected recordsets by employing XML as a medium of communication between these record sets and the DataStore.ADO.NET is the latest of the database access technologies that began with the Open Database Connectivity (ODBC) application programming interface (API). Microsoft introduced open database connectivity with the promise of creating a singular common access methodology for databases. ODBC has come a long way since those early days. Almost every major database in use today supports ODBC drivers, and third-party developers provide optimized driver versions. The primary focus of the ODBC is to provide a consistent interface to database data sources.
The article “ASP.NET Interview Questions and Answers” serves as an invaluable guide, offering comprehensive insights into this powerful platform. By exploring these latest questions and their concise answers, you can enhance your knowledge and enhance your chances of acing your ASP.NET interview. Stay prepared, stay confident, and embark on your journey to success in the ever-evolving realm of ASP.NET development.
Here are some valuable sources and references for your ease:
Choose classic ASP.NET when you have an existing application built on the .NET Framework and need to maintain compatibility with legacy code and libraries.
