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13 April 2017

ASP.Net MVC related questions

Hey Friends,
Now a days we can see there are many companies asking about the ASP.Net MVC related questions in their interview process. So I thought of keeping few questions which are related to MVC and ASP.Net MVC so that these questions will be help to all those who are going for the interviews or preparing for the ASP.Net MVC related questions.
Here I am keeping the questions related to all the versions of ASP.Net MVC by keeping in mind that interviewer can ask the questions from any aspect.

1.    What is MVC? 
Ans. MVC (Model View Controller) is one of the Software Architectural pattern which is built on 3 layers. So it is the pattern which basically talks about the separation of concern for a project. Here the 3 parts are having their own roles like:
a. Model - It is used as the Data Container or it can also have the business rules, functions, logic's etc.
b. View - It is mainly the UI (User Interface) part which is the main application built using the Web technologies like ASP.Net etc. It consists of the User Interface Design, representation of the information for the end users etc.
c. Controller - It is the mediator between the View and Model and used to control the requests and responses floating through the views and Model. The command, Actions, Events are the part of Controller in MVC. All the communication is done via Controller so we can say that Controller is the heart of MVC.

2.    What is ASP.Net MVC? 
Ans. ASP.Net MVC is the Microsoft product based on the core MVC pattern. The Microsoft has taken the core concept of MVC and Designed the ASP.Net MVC structure for the Visual Studio which helps the developers to get the automated structure and on it, they can built the applications.
ASP.Net MVC provides the structure with the separation of concerns where each part of ASP.Net MVC application is separate and has no link among them. Apart from the separation of concerns, the Microsoft has provided the way to communicate between the separate components by using the other additional logic and libraries. These libraries supports in the connection, communication between the components, databases and other external components as well with small effort.

3.    How ASP.Net MVC is different than MVC?
Ans. ASP.Net MVC is the inherited form of Core MVC where Microsoft has designed their MVC patterns based on the original core MVC concept. The Microsoft also provided the new MVC structure (ASP.Net MVC) which has the inbuilt capabilities of communication with their components, connection with the database etc. The ASP.Net MVC has the good support for creating mobile application. We can create the Mobile applications in ASP.Net MVC using the predefined template.

4.    What are the new features of ASP.Net MVC 2?
Ans. There are few major changes happened in the version MVC2. The Microsoft has more concentrated on the HTML Helpers, Validations support, Async controllers etc.Below are the few point which distinguishes the ASP.Net MVC 2 different than the previous versions:
a. New HTML Helpers with Strongly Typed
b. Model based validations- This is very useful feature where the validation is done in the Model and will be used throughout the application.
c. Automatic scaffolding feature also got introduces with this version.
d. Asynchronous controller support which enables the multiple tasks to run simultaneously.
e. Html.RenderAction introduced to render the section/part of the page.

5.    Explain MVC Architecture?
Ans. MVC architecture comes with 3 major components-Model, View and Controller.

The main objective of the MVC design pattern is to separate the logic with the UI. So the separation of Concerns is one of the biggest advantage of the MVC design pattern where the UI is separate with business logic.
The user sends the request and the request is taken by the Controller which is heart of the MVC model and takes care of all the actions and events happens in the View. The controller checks whether the request required the Model intervention and if so then call the model to serve the database operations and get the result back. Based on the Model data, the View will be populated. So the Model and View are nothing but the mapping of each other. View is always gets populated based on the Model and not rendered.

6.    What are the new features of ASP.Net MVC 3?
Ans. a. Scaffolding option for the speedup process
       b. Razor engine with the new razor syntax for good readability of the View code.
       c. HTML 5 support
       d. Model based validations
       e. Model Binders to bind the model with View
       f. Action filters
       g. Nuget enabled
       h. Output caching for partial page
7.    What are the new features of ASP.Net MVC 4?
Ans. a. Mobile support by adding a new Mobile Project template
       b. Web API added for the HTTP requests
       c. Task class support with Async methods
       d. Bundling and Magnification
       e. Login with the social networking websites
       f. Support of Windows Azure SDK
       g. Display modes for the webpage and mobile layout page
8.    What are the new features of ASP.Net MVC 5?
Ans. a. One ASP.Net for all type of Web templates
       b. Bootstrap enabled for the MVC 5
       c. New Authentication Filter for Controller/Controllers
       d. Attribute Routing
       e. New Scaffolding option
       f. Filter overrides feature
9.    Explain ASP.Net MVC application life cycle?
Ans. The application life cycle of MVC includes the request, processing, filtering and execution and then finally the response back to the requester. The request first goes to URL routing module(HTTP Module) and there it gets decided that whether this is MVC request and will be handled or not. Now if the request is for MVC application, the URL routing module selects the first route which is satisfying the requested URL. As soon as the first match found for the requested URL, the process for the execution begins with the Controller and Model(if any) and the response sends back to the browser.

10. Advantages of MVC Framework?
Ans. Below are the advantages of MVC framework:
       a. Separation of Concerns
       b. Light weight
       c. No round trip for the layers
       d. Decoupling between the layers
       e. No dependencies between the Model, View and Controller  
11. What do you mean by Separation of Concerns?
Ans. Separation of concerns means all the three components (Model, View and Controller) are not dependent to each other. We can have a single controller which can server the request and can use any number of Views to populate.

12. Where do we see Separation of Concerns in MVC?
Ans. We can see the separation of concern when we add/remove a View, it will not impact on rest of the application because its all depends on when you call, then only it will be used. if there is no call for the View, the application can just keep the view or model with no dependencies.

13. What is Razor View Engine in ASP.Net MVC 3?
Ans. Razor View engine is the new engine which the Microsoft has introduces with the ASP.Net MVC 3. So from MVC 3 onward, we can see the MVC application will support ASPX as well as Razor view engine. So when we use .aspx to develop our Views, it will use the ASPX engine to execute and when we use the Razor Views(.cshtml or .vbhtml), then it will use the Razor view engine to execute them.

14. Explain the advantages of using routing in ASP.NET MVC?
Ans. There are many advantages of using routing mechanism in ASP.Net MVC like:
a. To keep the URL clean- as in MVC, the default format for the URL is "". This URL shows that GetCustomer will give the customer details for the id as 10.
b. Discovering the URL by End User- The end user can easily discover the URL details like in above URL, the end user can discover that this URL will give the Customer details for the customer id 10.
c. Avoiding the database id's in URL- with this, we can avoid the id's which are defined in the database.

15. What are the things that are required to specify a route ? Which is a better fit, Razor or ASPX?
Ans. RouteConfig.cs is the class used to define the routes. This file is placed under the App_Start folder. The file RouteConfig.cs contains one default route, however the programmer can define other routes as per their requirements.

To Specify a route, we need Name and URL of the route. The default URL contains the Controller Name, Action name and the id(if required). By this route, the actual URL gets mapped and if it maps correctly, the view will get displayed, else it shows the 404 error (file not found).

16. How can you do authentication and authorization in ASP.Net MVC?
Ans. Windows and Form Authentication are available for the Authentication & Autherization in ASP.Net MVC.

17. How to implement Windows authentication for ASP.Net MVC?
Ans.  To Implement the Windows Authentication, it is similar to other application where we can define the authentication mechanism in the config file. In the same way, we can implement the Windows Authentication & Authorization using the below snippet:
Now, we can retrict the particualr use to access the controller as below:

We can also restrict the action methods by using the same attribute.

18. How do you implement Forms authentication in ASP.Net MVC? Mention some of the return types of a controller action method.
Ans. The Form Authentication implementation is similar to the ASP.Net form authentication where we need to check the user credentials in each forms to validate the user and then provie the access.
For this, we need to first define the Form Authentication Mode in Web.Config file as:

Now once we define the Form Authentication, we can check the user and set the cookies as:

We also need to include the "using System.Web.Security;" as namespace to get the FormAuthentication class.
The above code is checking the user credentials and then setting it in AuthCookie. Now onwards wherver we want to check for the Form Authentication, we just need to add the [Autherize] attrivute to the action methods as:

19. Is ASP.Net MVC suitable for both Windows and web applications?
Ans. No, ASP.Net MVC is primarility made for the Web Applications development. For the Windows Application, MVP is most suitable.

20. What are the benefits of using ASP.Net MVC?
Ans.  The major benefits using ASP.Net MVC are:
a. Separation of concern- separate code behind file
b. Automated testing - testing of the logic with no UI

21. Is MVC different from a three layered architecture?
Ans. Yes, MVC is different than the 3 layered architecture in terms of UI layer(no code behind or separate code behind in MVC), the communication between layers, routing mechanisms etc.
In 3 Layered architecture:
UI <------> Business logic Layer <-------> Data Access Layer
Controller -----> Model
     |                      |
UI(View) <-------

22. What is the latest version of ASP.Net MVC?
Ans.  The current version of ASP.Net MVC is 6. This version of ASP.Net MVC is also called as ASP V-Next which is the common framework to develop MVC, Web Pages, Web API, Signal R applications. Also it can be self hosted and not depends on IIS for hosting. 

23. What is the difference between each version of ASP.Net MVC?
Ans. Below are the features in each of the version in ASP.Net MVC:

a. Async Controller
b. DefaultValueAttribute in Action Method
c. Area concept
d. Bind binary data with the Model binder
e. Model based validations
f. DataAnnotations support
g. Html.ValidationSummary helper method

a. Razor syntax and Razor engine
b. Support for HTML 5
c. Automatic templates available for the Create, List, Edit, View via Scaffolding

a. Web API introduction under ASP.Net MVC
b. Mobile project templates
c. Bundling & Minification
d. Task support for Asynchronous controller
e. Azure SDK
f. Enable login using 3rd party sites like Facebook, Google, Twitter etc by OAuth & OpenId

a. Attribute based routing
b. One ASP.Net
c. Bootstrap in MVC Templates auto-enabled
d. Authentication Filters
e. Filter Overrides

a.  Merging of ASP.Net MVC and Web API
b. Inbuilt DI(Dependency Injection)
c. JSON based project structure(Added JSON)
d. Nuget package based
e. Auto-build by save using Roslyn compiler.
f. Open Source(Runs on Mono, Linux & Mac)

24. What are HTML helpers in MVC?
Ans.  To render HTML controls in View, HTML Helpers are used.
e.g. Html.TextBox("Address")

25. What is the difference between "HTML.TextBox" vs "HTML.TextBoxFor" in ASP.Net MVC?
Ans. Both the "HTML.TextBox"  and  "HTML.TextBoxFor"  will produce the same output but the "HTML.TextBoxFor" is strongly typed while "HTML.TextBox" is weakly typed.
e.g. Html.TextBox("Address") // weakly type
it will give the same output as  
e.g. Html.TextBoxFor(x => x.Address) // strongly type

26. What is routing in MVC?
Ans. Routing in MVC is used to define the URL structure. It also map the URL to the controller and Action method. Fore more details, go to the Q.15

27. Where is the route mapping code written?
Ans. RouteConfig.cs is the file where the route is configured. Fore more details, go to the Q.15

28. Can we map multiple URLs to the same action?
Ans.Yes, we can map the multiple URL's to the same action method.

29. How can we navigate from one view to other view using a hyperlink?
Ans. Simply, We can use the ActionLink method and [provide the controller and action method as the parameters. e.g.

30. How can we restrict MVC actions to be invoked only by GET or POST?
Ans.  We can restrict the actions to be called by GET or POST by decorating the action method by HttpGet or HttpPost as below:

31. How can we maintain sessions in MVC?

Ans. There are various ways to maintain Sessions like-
a. Use Session variables
b. Use Hidden Fields and Html Controls
c. ViewBag - uses Dynamic keyword internally. No need to do casting.
d. ViewData - used to pass data from Controller to View. Casting is required.
e. TempData - between controller to controller or Action to action. It uses Session internally.

32. What is the difference between tempdata, viewdata, and viewbag?
Ans. TempData maintains the data for complete request while ViewData can be used from controller to View.See Q.31

33. What are partial views in ASP.Net MVC?
Ans. Partial View is like User Controls in ASP.Net so they can be used in other views. We can embed as many Partial Views in Main View.

34. How do you create a partial view and consume it in ASP.Net MVC 4?
Ans.  While creating a new view, we can see the option is given to make this view as partial. We need to check the checkbox "Create a Partial View". Once we design and do all the stuff related to filling the data in to the partial view, we can call it using the Html.RenderPartial("MyPartialView") into our main view.

35. How can we do validations in ASP.Net MVC?
Ans. In ASP.Net MVC, there is no need to do validation in the page(view). We can do the Model based validation which will be done in the Model using the Data Annotations.
To use the Data Annotation, we need to include
using System.ComponentModel.DataAnnotations; namespace in to our model.

36. Can we display all errors in one go? or Validation summery in ASP.Net MVC.
Ans. Html helper class contains a method with the name as ValidationSummary which can be used to show all the errors in one go.
e.g. Html.ValidationSummary()

37. How can we enable data annotation validation on the client side?
Ans.  To enable the Data Annotations at the client side, first we need to include the JQuery validation file and then call the Html.EnableClientValidation() method.

38. What is Razor in MVC?
Ans. Razor is the new engine to parse the MVC code. From ASP.Net MVC 3, Microsoft has introduces this engine. So in ASP.Net MVC 3, there are 2 View Engines- Razor and ASPX

39. Why Razor when we already have ASPX?
Ans. The Razor view Engine is lightweight as compare to the ASPX view engine. Razor engine has quite readable and simple syntax's.

40. How to implement AJAX in MVC
Ans. There are 2 ways to implement AJAX in MVC:
a. By using JQuery
b. By using Ajax Libraries

41. What kind of events can be tracked in AJAX?
Ans. AjaxOption is having the events like OnBegin, OnComplete, OnFailure, OnSuccess etc.

42. What is the difference between ActionResult and ViewResult?
Ans. ActionResult is the base class for all the result types. All the result types are inherited from the ActionResult class. The Derived results types are like -  
ViewResult, JsonResult, FileContentResult etc. 
Whenever we are not sure that what type of result will be returned, we can simply use the ActionResult as the return type.
The ActionResult result type is mainly used for the dynamic view where the result type is not defined. It returns based on the condition.
ViewResult is the derived type and used when the return type of the Action is View. It is specific to the View Type and so can be used only when we are sure that the return type of the action will be only view.

43. What are the different types of results in MVC?
Ans. There are various type of results in ASP.Net MVC. Below are the few:
ViewResult - It is used to renders view type as the result.
PartialViewResult - It is used to renders partial view type as the result.
EmptyResult - To return empty result type
RedirectToRouteResult - To redirect to URL which is determined by the route engine.
JsonResult - to return the JSON format data
JavaScriptResult - To return JavaScript type result

FileContentResult - To return a file type result.

44. What are ActionFilters in MVC?
Ans. If we want to perform some login when the action is executing, we can use ActionFilters to do this.
For example, after the action is completed, we want to do some post processing, we can use ActionFilters.
There are mainly 4 types of action filters available in MVC:
a. Authorization filters
b. Action filters
c. Result filters

d. Exception filters
We can also create the ActionFilter by implementing the methods available in IActionFilter interface in the controller class. This interface contains 2 methods- OnActionExecuted and OnActionExecuting
These interface methods take the ActionExecutedContext as the input parameter.

45. Can we create our own custom view engine using MVC?
Ans.  Yes, It is possible to create the Custom View Engine in ASP.Net MVC by implementing IView interface to the View class. 
We need to implement the Render method of the view. Then we need to Override the CreateView method in EngineProvider class. Finally we need to add the provider class to the App_Start method. 

46. How to send result back in JSON format in MVC
Ans.  To Send the results back to the JSON format, we can use JsonResult as the return type of the action.
In the action method, we can use Json method which will give the Json format of the data.
public JsonResult getEmployee()
    Employee objEmployee = new Employee();
    objEmployee.ID = "9001";
    objEmployee.Name = "Ramesh";
    return Json(objEmployee,JsonRequestBehavior.AllowGet);

This will give the Json result in the browser.

47. What is WebAPI?
Ans. WebApi is the technology through which we can expose our data over HTTP using ReST principals.
WebAPI is very light weight and only HTTP is used for the data transfer.

48. But WCF SOAP also does the same thing, so how does WebAPI differ? With WCF you can implement REST, so why WebAPI?

49. How can we detect that a MVC controller is called by POST or GET?

50. What is Bundling and Minification in MVC?

51. How does bundling increase performance?

52. How do we implement bundling in MVC?

53. How can you test bundling in debug mode?

54. Explain minification and how to implement it. How do we implement Minification?

55. Explain Areas in MVC?

56. Explain the concept of View Model in MVC?

57. What kind of logic view model class will have?

58. How can we use two(multiple) models in a single view?

16 December 2015

3-6 yr Experience Interview Questions in .Net Technologies

Hai Friends,
Below I am posting the questions and answers for the short questions for 3-6 years experience guys. These questions will be helpful for those who are either preparing for the interview or attending the interviews. This will also be helpful for the last minute preparation in quickest way.
If anyone has better answers, please reply to this post and I will include the better answer to the post as it will be helpful for all of us.

CLR and C#

1. Types of Authentication IIS.
A. Authentication is the process which helps web server(IIS) to check and confirm the identity of the client who request to access the website.
Types of Authentication: 
a. Http Authentication: Basic Authentication, Digest Authentication
b. Integrated Windows Authentication: NTLM(Network Lan Manager), Kerberos
c. Client Certificates Access
d. Anonymous and UnAuthenticated Access
e. Logon-Redirection based: Form Authentication(IIS 7.0)

2. Types of Authentication and Authorization in ASP.Net.
A. Types of Authentication: Windows Authentication, Forms Authentication
Types of Authorization:- File Authorization and URL Authorization

3. ASP.Net Life cycle.
A. In ASP.Net, the request starts with the client and processed through IIS.  In IIS, there are 2 utilities- INetInfo.exe and ASPNet_ISAPI.dll.
The InetInfo.exe hosts the worker process and checks for the syntax and semantics of the request, while ASPNet_ISAPI.dll is used to filter the .aspx files(based on the extension). After the URL request split into 2 parts- 
Virtual directory name and Web Page name. 
The worker process which is nothing but the application factory basically contains all the virtual directories and checks for the current virtual directory. If this is first request, then there will be no Virtual directory available. Now the worker process (W3wp.exe) creates a memory area called as AppDomain to check for the current page. As AppDomain is the Page Handler factory so it contains all the processes pages. If this is the new page then it will not find here. The request further moves to the HttpPipeline where the actual execution of the page happens by using the ProcessRequest method and creates the events(init, load, render, unload) of the page. After creation of event and execution of all the event, the HTML page returned back to the user.

4. ASP.Net Page Life Cycle.
A. There are few events which gets generated during the page execution like: Page_BeginRequest, Page_Init, Page_Load, Page_Prerender, Page_Render, Page_Unload etc
For the details of the page life cycle, you can follow the previous question.

5. What are types: Value Type and Reference Type?
A. DataType specifies Type of the data as well as Size of the data. There are 2 type of DataTypes in C#:
a. Value Type: Value type holds data directly, Value type stored in the stack memory, we can get the direct value of the value types. Value type data type can’t be null.
b. Reference types: This type does not hold the data directly. They hold the address on which the actual data present. They stored in heap memory, Can have default values.
We can make and work with null reference type.

6. Boxing and Unboxing: Terminology, Advantages and Disadvantages.
A. Converting the Value type data into the Reference type is called as Boxing
byte b= 45;
Object o = b.Tostring();
Converting the Reference type data and keep its value to stack is called as the Unboxing.
Object o=10;
Int i= Convert.ToInt32(o.ToString());
The Advantage of boxing and unboxing is that we can convert one type of the object to another type. The disadvantage is that it requires lot of memory and CPU cycles to convert from one type to another type.

7. What is Type Safety?
A. TypeSafe is a way through which the application or framework that the memory will not be leaked to outside environment. E.g. C# is the type safe language where you must have to assign any object before using it. In VB.Net it will take the default value. So C# is the type safe language while VB.Net is not.

8. What is Strong Name?
A. Strong Name (SN) is used to make the dll as the unique not by its name but by its version as:
SN -k fileName.dll
Now it will have the unique name with respect to the version. This assembly when placed in the GAC, it will treat as the unique with its version number and other details. 2 assemblies with the same name can exist in the GAC but both will have different version. The CLR takes the latest version assembly while running the application.

9. What are Extensions, modules and handlers?
A. HttpModule and HttpHandler are the utilities which are used in the HttpPipeline under the ASP.Net page life cycle. When the request received to Http Pipeline, the HttpModule checks for the Authentication of the request and then it route the request to the respective handler. After that HttpHandler takes that request and process it. Once the request is processed through handler, again the HttpModule takes the response and send it back to the worker process and finally to the user.

10. What is worker process?
A. Worker process (w3wp.exe) is an executable which is also called as the Application Factory. This is used for the execution of the request and handling of the request for the web pages.

11. CLR and DLR?
A. CLR (Common Language Runtime) is the utility in the .Net framework to run the application. It is the runtime engine which actually executes the application with many responsibilities like taking care of memory management, versioning, CasPol etc.
DLR is new with .Net 4.0 which is the Dynamic Language Runtime and used to run the application on the fly wherever required. CLR runs as statically while DLR runs dynamically.

12. In case more than one dll versions of an installable is installed, which version is invoked by default?
A. By default the CLR will take and invoke the latest version of the dll and execute it accordingly. There could be the same name assemblies exists in the GAC but they will have different versions altogether for their uniqueness.
So while running the application, CLR takes the latest version assembly and use in the application.

13. What are Globalization and localization? How to implement them?
A. Globalization is the concept of developing the application in more than one language while the Localization is used for a particular language. Like if we develop the application in more than one language we need to create the resource files (.resx) by using System. Globalization and when we open the application in a particular language, then the localizations used to convert that application to the selected language.

14. What is assembly, GAC? Where they are physically located?
A. Assembly is the collection of classes, namespaces, methods, properties which may be developed in different language and packed as a dll. So we can say that dll is also called as assembly.
There are 3 types of assemblies- 
- Private Assembly, Shared Assembly, and Satellite Assembly.
GAC (Global Assembly Cache)- When the assembly is  required by more than one project or application, we need to make the assembly with strong name and keep it in GAC or in Assembly folder by installing the assembly with the GACUtil command.
To make the assembly with strong name:
SN -k MyDll.dll
And to install it in GAC:
GacUtil -i MyDll.dll
GAC assemblies are physically stored in Assembly folder in the system.

15. How to configure HTTPS for a web application?
A. To configure the HTTPS (HTTP with Secure) for the web application, we need to have a client certificate. The client certificates can be purchased from the trusted providers and then we need to install that certificate for our site. By implementing the HTTPS, all the data which is passing will be in encrypted format, while makes the website more secure.

16. What are Inproc and Outproc in session? Where are session data stores in these cases?
A. Inproc and Outproc is the types of Sessions where the session data can be stored in the process memory of the application server(IIS) and in the separate state server.
When the session data is stored in the process memory(AppDomain) of the server(IIS), the session is called as the Inproc server. In this case when the server is restarted, the session data will be lost. So In the Inproc session mode, the session data stores in the memory object in AppDomain in Application Worker Process(AspNet_wp.exe)
When the session data is stored in the separate server like in state server or in Sql Server, the type of session is called as the Outproc session. In this case, if the server where the application is running is restarted, the session will be still remain in the separate servers.
So in the  inproc session state, the session data is stored in the Process memory of the Server where the application is running.
In the Outproc session state, the session data is stored in the separate server- may be state server or in sql server.

17. When the View state is saved, and when is it loaded? How to enable/ disable View states?
A. View State data is stored in the current page in base64 encoded format. It gets loaded with the page and displays the values to the controls after the decoded. Internally it actually saves the check-sum of all the control data where the view state is that when the page gets loaded due to any post back, it again finds the check-sum and then decodes the Base64 encoded string and gets back the same data to the controls. We can see the view state base64 encoded string in View Source of the page. It will be like _VIEWETATE="DSDSDF8DGDGDFGFD5FDGGDJFF23BNN457M9UJOG" this.
View state won't take the client or server memory to keep the view state data.

18. Difference between GET and POST. Which one is more secure?
A. GET and POST methods are used for the data transfer between the web pages. GET mainly used for small data which is not secure because in case of GET method, the data which we are passing will be visible in the url so we can't keep the secure data which will be visible in the url. There is also limited data which can be passed in case of GET method (max 255 character).
POST is used for transferring the huge data between the pages where we can keep the secure data and can transfer it. In case of using the POST method, the data which is transferring between the pages will not be visible so it is more secure than the GET method. Also there is no limit for POST method to post the data to the next page.
POST is more secure.

19. What are Razor engine? How is it different from ASPX Engines?
A. Razor engine is the new execution engine in the ASP.Net MVC 3 which is mainly used to convert the rezor syntax views to HTML page in the MVC applications. It takes the cshtml pages as the input for the ASP.Net MVC application and then render to the HTML as the output. The ASPX engine takes the aspx code and then renders to the HTML.

20. Pros and cons of JavaScript and AJAX.
A. JavaScript is a scripting language and mainly used for client side validation. We can validate the client side data before sending to the server. So by this we can improve the performance of the application.
Ajax is Asynchronous JavaScript and XML which is used for the Asynchronous calls to the server. It uses the JavaScript/JQuery for making the call and use XML for the Data Transfer. It basically uses the XmlHttpRequest for the asynchronous calls to the server and communicates with the XML data which is platform independent. So Ajax can be used with any technology.

21. In how many different ways JavaScript code can be used/called in an application?
A. JavaScript can be used for Client Side validation, can also be used for calling of server side methods and functions, can be used for calling the web services, WCF service, Web API's, Calling the Controller and Action methods in ASP.Net MVC etc.

22. What needs to be done to call a JavaScript function from code behind?
A. If we want to call the JavaScript function from the code behind, we need to attach the JavaScript to the events in the page_load event as:
protected void btnSave_cliekc9object sender, EventArgs e)
 btnSave.Attributes.Add("onclick,"JavaScript: retrun Validatedata();");
Here ValidateData is the JavaScript function which can be used to validate the page data and if validation fails, it will return and will not execute the server side btnSave_click event.

23. Difference between Server Controls and User controls?
A. User controls are used for the re-usability for the controls in the application. By using the Web User Control template, we create the new user controls and then we can use the same control in the various pages. User controls can be created by combining more than one control to extend the functionality of the existing controls. To use the user controls, first we need to register them in the web page where we want to use that control. A separate copy is needed in each page where we want to use the user control. User controls can't be included into the toolbox.
Web Server controls are those controls which can be found in the toolbox and can be directly drag to the application like other controls textbox, button etc. For the web server control, only 1 copy of the control is needed irrespective of the number of web pages. If we want 10 text-boxes to be added in our web page, we need only 1 copy of the textbox in the toolbox and can be dragged 10 times.

24. Difference between Var, object and Dynamic types.
A. var is the keyword introduced with .Net 3.5 and used to store any kind of data like data-set, data table, int, float, char etc. We can keep any kind of data into the var variable.
var myVar = new String[] {"hello", "world!!"} ;
Here the myVar is the var type variable which is used to store the string array. Like this we can store any type of data into the var.
Object is the type which is used to store the objects of any kind. These objects need to be type cast when used.
Like object myObject = "Hello"
Here the myObject variable of object type is used to keep the string variable. Now when we want this variable value, we need to typecast it like
string strvar= (string) myobject;
Var is the compile time where the type of the var variable gets defined at the compilation of the program. Once we define the type during compilation, we cant make the changes of the type during run time or at the later stages.
Let's say, if we define like
var myVar = new String[] {"hello", "world!!"} ;
so here myVar variable will be of string array. Now after this, I can;t make it like:
var myVar = 10 ;
If we do this, it will throw error.
Dynamic- It’s a keyword introduces with the .Net 4.0 and used to keep the data similar to the var keyword. The type of Dynamic type can be changed even at run time.
So if we define like:
dynamic myVar = new String[] {"hello", "world!!"} ;
Then the myVar is of type string array. Now if we do like:
dynamic myVar = "Hello" ;
Now the myVar type will be used as string type. So we can change the type in case of dynamic.
The difference between the var and dynamic is that the dynamic variable uses the same memory location to store the object and not changes throughout the application.

25. Difference between Functions and methods.
A. In.Net terminology, both function and method are same. In general, we use method in server side code of .Net but in scripting language we use function like JavaScript function.
Here the difference can be function always returns a value whereas method may or may not. It depends upon the return type of the method. 

26. Difference between Abstract classes and Interface. Explain with scenario where to implement one?
A. Abstract Class: Collection of the Abstract (Incomplete) and Concrete (complete) members is called as the Abstract class. If there is at least one abstract member in a class, the class must be declared as abstract class.
When there is the similar behavior, we can use the abstract class.
e.g. We want to calculate the area of few shapes. As this is not generic to the application. We have few shapes - like Circle, Ellipse, Parabola, Hyperbola, Triangle etc.
So we can create an abstract class and implement it like below:
public abstract class MyAbstractClass
 // some other concrete members
 public abstract void Area();// abstract method
Now in the child class, let’s say i have a circle class and want to calculate the area of the circle:
public class Circle: MyAbstractClass
 public override void Area()
  // calculate the area of the circle
In the similar fashion, we can calculate the area of other shapes.
Interface: Collection of abstract members is called as the Interface. When the behavior is not similar, we need to use the interface. All the members of the interface
must be overridden in the child classes.
e.g. Print functionality of the application can have an interface method like:
interface Inf
 void Print();
Now as this is the generic functionality and can be implemented in any of the class so we have taken it as interface. We can implement this functionality into any page like:
class MyClass: System.Web.UI.Page, Inf
 public void Print()
  // implement details about the Print method
// Here we can implement any kind of print-like print to excel, xml, word all depends on the our decision.

27. Different forms of Polymorphism. Differences between Abstraction and Polymorphism.
A. Polymorphism is to use the same function in many forms. The polymorphism is of 2 types-
a. Classical polymorphism (Overloading)
b. AdHoc polymorphism (Overriding)
Polymorphism = Poly(many) + Morphism(Forms) 
Overloading: When the runtime (CLR) find the behavior of class members at the compilation of the program, it is called as the Classical polymorphism or Overloading. In this, the method name is same but prototypes (method + parameters) are different and it is implemented in the same class.
public class MyClass
  public int  Add(int a, int b)
   return a+b;
  public int  Add(int a, int b, int c)
   return a+b+c;
Overriding: When the runtime (CLR) find the behavior of class members at the runtime of the program, it is called as the AdHoc polymorphism or Overriding. In this, the method name as well as the prototype (method + parameters) is same but they are implemented in the different class. We use virtual keyword in the base class method to override in the child class using the override keyword.
public class MyBaseClass
 public virtual void Show(string  message)
  Console.WriteLine(“Your message is : ”+ message);
public class MyChildClass: MyBaseClass
 public override void Show(string message)
  Console.WriteLine(“Your new message is : ”+ message);
Abstraction is the behavior to get the required functionality. To implement the abstraction, we use access specifiers where if we declare the members as private, it means they will be available only to the current class and if we make them as public, the other classes can also use them. So Abstraction is used to show only the essential features It is also used to hide the unnecessary data which is not relevant but present.
Abstract keyword is also used to get the abstraction behavior. We can use Abstract Class and Interface to implement Abstraction.

28. What are Delegates and Events?
A.  A Delegate is an object, which points to another method in the application. Delegate holds- name of the method, arguments of the method (if any) and the return type of the method.
See the below points regarding the Delegate:-
·          delegate keyword is sealed type in System. Multicast namespace.
·          Delegate works like a function pointer in C language.
·          Delegate holds the address of the function.
·          Delegate hides the actual information which is written inside the method definition.
·          A delegate can hold address of a single function as well as the address of multiple functions.
·          There are 2 types of delegate- 
           - Single cast delegate (hold single function) and 
           - Multicast delegate(hold multiple functions).
·          Addition and subtraction are allowed for the delegates but NOT multiplication and division. It means, we can add delegates, subtract delegates etc.
e.g. To create a single cast delegate, first we can create a class with a method as:
public class DelegateDemo
 public void Show(string msg)
Now we can call the method Show using the delegate as:
public  delegate void MyDelegate(string message); //declare delegate
now we need to create the object of the delegate with the address of the method as:
DelegateDemo obj = new DelegateDemo();//class object
MyDelegate md= new MyDelegate(obj.Show(“Hello World!!”));
md(); // call the delegate
We can create the events and event handler by using delegate with the below syntax:
public delegate void textChangedEventHandler(Object sender, TextEventArgs e)
This event handler will be used to handle the textbox textchanged event.
More details about the delegate and events can be found at the below link:

29. Covariance and Contra-variance.
A.  covariance and contravariance are the new features added with the .Net 4.0. They are basically used for the implicit reference conversion for different .Net types like array, delegate, and generic etc.
You can go to the below link for more details with the examples that how we can use the covariance and contrvariance to implicate reference conversion:

30. What are Extension methods?
A. Extension methods are special types of methods which are static methods but called as the instance methods.  The extension methods are added with the .Net framework 3.5 and with the Visual Studio 2008.
These methods won’t affect the existing class and the label. These methods are used for the extra behavior which the calls can provide. There is no need to build the class again if we add any extension method to the class.
There are various inbuilt methods added in .Net 3.5 with the introduction of LINQ. We can see the extension methods like Order By when we use the Linq as:
int[] numbers = { 10, 45, 15, 39, 21, 26 };
var orderedNumbers = numbers.OrderBy(a => a);

31. What are Anonymous methods and Lambda Expression?
A.  Anonymous methods are those methods which does not have the name. As they don’t have the name, so there is no way to call these methods. These methods are created by using the delegate as below:
button1.Click += delegate{listBox1.Items.Add(textBox1.Text)};
Lambda Expression: It’s an easy way to create anonymous functions. It is also an anonymous function which has the capability to contain expressions and statements. We can create the delegate and expression tree types using the lambda expression.
For more details regarding the anonymous method and lambda expression, we can go through the below link:

32. Multithreading. How to implement Multithreading?
A. Executing more than one processes simultaneously is called as multithreading. To implement the multithreading concept, we need to use the System. Threading .dll assembly and the System. Threading namespace.
To write the thread program, we need to create a class with the method. Now we can create the thread object and then pass the method by using the class object to the method.
After that we need to create the ThreadStart delegate which will call the actual method of the class.
You can go through below link for more explanation and other details regarding the implementation and the code snippet:

33. Which interface is used to-
a. Convert Boolean values to Visibility values?
b. Compare two integer values?
c. Compare String values?
A. Check the below interfaces which are used in these scenarios:
a. Convert Boolean values to Visibility values?
b. Compare two integer values?-  IComparable interface
c. Compare String values? IComparer interface

SQL Server

34. What is the difference between a View and a Cursor?
A. View: It is one of the database object which is also called as virtual table. We can also say that it is a window through which we can see some part of database. View is also called as stored query because we are going to fetch data using View.
View does not contain any data. It’s just a virtual table which is used to get the records from the base table for which the view is created. View is faster than ad hoc queries because when we create the view and execute it once. Next time onwards it will be available as the compiled format. So whenever the view is called, it will just execute rather than compiling.
Cursor: Cursor is a database object which is also the buffer area and created as a result of any sql statement to hold the intermediate values.
Cursor is used to format the rows individually. By using the cursor, we can process the individual rows. There are 4 types of cursors in Sql Server-
a. Static Cursor
b. Dynamic Cursor
c. Key set cursor
d. Read-only cursor

35. How to execute multiple update on different conditions in a single query?
A. To execute multiple update using a single Sql update statement is the new feature available with the SQL Server 2008. In this, we can update multiple rows using a single update command.

36. Left outer joins and Right Outer joins
A. Joins are used to retrieve data from more than 1 tables using some conditions. There are 3 types of outer joins in SQL Server database-
a. Left Outer Join
b. Right Outer Join
c. Full Join
In order to extract the matched rows from both the tables and unmatched rows from the first table, left Outer join is used. The syntax for left outer join condition is:
T1.Col1* = T2.Col1
In order to extract the matched rows from both the tables and unmatched rows from the second table, right Outer join is used. The syntax for right outer join condition is:
T1.Col1 = *T2.Col1
In order to extract the matched rows from both the tables and unmatched rows from the first table and then unmatched row from the second table, full join is used. The syntax for full join condition is:
T1.Col1* = *T2.Col1

37. Exception handling.
A. Exception Handling is the way to handle the unexpected error at runtime of the application. From the SQL Server 2005 version, try…catch block is also supported to catch the exceptions in SQL Server database. There is various other ways to catch the error like using Global temporary variables @@Error, inbuilt method RaiseError etc. 

38. What is Performance Tuning? How do you implement it.
A. Performance Tuning is the process through which we can optimize the SQL Server objects like functions, triggers, stored procedure to achieve high response time to the front end applications. In the performance tuning process we generally check for the below point and optimize the objects processing:
a.  Through Query Execution plan, check for the processing time of the query execution.
b. Check the join conditions and break all the condition for executions of the queries individually.
c. Check for the error prone process, conditions in the queries.
d. Check for the loops whether they are terminated if any error occurs.
e. Check for the processes which are taking more time in execution and how to reduce the response time.

39. Difference between Having and Where clauses.
A.  When the 'where' clause is not able to evaluate the condition which consists of group functions, Having clause is used. Having clause is always followed by the Group By clause.
'Where' clause is used to filter the records based on the conditions. If there is the requirement to get the group data in the select statement and where clause is not able to get it, we can use the Having clause.
e.g. Display DeptNo, No.of Employees in the department for all the departments where more than 3 employees are working

40. Difference between Temp tables and Tables variables?
A. Temp Table in SQL Server:
a. Temp table are the special type of tables which are used to store the intermediate data of the actual table.
b. Temp tables are only visible to the current sessions of the sql server instance. When the session end, these table data automatically drops.
c. We can’t join the temp tables as they don’t allow the foreign key constraints.
d. Temp tables are created in TempDB database.
e. We can use the same temp table name for the different user sessions.
f. Mostly used in stored procedure to handle the intermediate data.

41. What does @ and @@ suffixed by property names specify?
A. @- This is used for the variable declaration
e.g. @name varchar2(50)
@@- This is used for the Global variable declaration
e.g. @@Error=0

42. Self-join queries.
A. Self-Join is a type of join which is used to join the same table by creating the multiple instances of the same table. So we can join 2 instances of the same table in case of self-join. This type of join is used when there is the requirement to get the referenced data which is available in the same table.
e.g. A table contains EmpId, Ename and ManagerId
As the manager is also an employee. Now if we want that who is the manager of which employee. In this situation, we need to create the instance of the same table and get the required data as:

43. Types of Index.
A.  Index is one of the database objects which is used to improve the performance of the database queries. It reduces the table scan while retrieving the data from the database and the search gets fast-
There are 2 types of indexes used in the SQL server:
a. Clustered index
b. Non clustered index
There are 3 more types of index but those comes under the above two-
a. Unique index
b. Composite Index
c. XML Index-added in SQL Server 2005

The index basically works on searching like binary tree where the root value is the finding value and it will be compared with the partitioned value of the tree.

44. Difference between Primary key, Unique key and Candidate key?
A. Primary Key- It is a key to make the unique identification of the row in a table. It doesn't allow null values in the primary key column. We can create the lookup columns based on the primary key. One table allows maximum of 1 primary key and in 1 table, we can create the primary key column by using 16 columns. Due to one of the normalization rule, we have to create primary key for the table to make the rows unique.
Unique Key:- (Primary Key + Not null) is called as unique key. Unique key is also used to make the rows as unique in a table. The only difference between primary key and unique key is that primary key does not allow null value while the unique key allow. The limitation of the null in unique key is that it allows only one Null value. So only in one row, we can make the key as null for the unique key.
Candidate key- The key other than primary key, to make the rows as unique is called as candidate key. In candidate key, we take the columns which are not in the primary key and make the key for uniqueness of the row.

45. What is the default value for Datetime. What are Min and Max values for Date in 2008.
A.  The default value of Date is CURRENT_TIMESTAMP
Below are the new date and time values in Sql Server 2008:
In SQL Server 2008:
1. DateTime2

Min Value: 0001-01-01 00:00:00.0000000
Max Value: 9999-12-31 23:59:59.9999999
2. Date
Min Value: 0001-01-01

Max Value: 9999-12-31

You can go through the below link for couple of work around:


46. What is WCF also known as?
A.  WCF (Windows Communication Foundation) is also know as  Indigo by its code name.

47. Difference between WCF and Web Services?
A. Below are the main differences between the WCF and Web Service:
Web Service:
a. Can be hosted in IIS only
b. Only two types of operations affects- One-Way, Request-Response
c. To serialize the data use System.Xml.Serialization
d. To encode the data use- XML 1.0, MTOM, DIME, Custom
e. Web Service can be accessed through HTTP channel.
WCF service:
a. Can be hosted in IIS, Self Hosting, WAS, Windows Services etc
b. Three types of operations affects- One-Way, Request-Response and Duplex
c. To serialize the data use System.Runtimel.Serialization
d. To encode the data use- XML 1.0, MTOM,Binary, Custom
e. WCF Service can be accessed through HTTP, TCP, Named pipes, MSMQ,P2P etc.

48. What are Endpoints?
A. The collection of Address, Binding and Contract is called as End Point. In Sort,
EndPoint = A+B+C
Address (Where)-  It means where the service is hosted. URL of the service shows the address.
Binding (How)- How to connect to the service, is defined by the Binding. It basically has the definition of the communication channel to communicate to the WCF service
Contract (what)- It means what the service contains for the client. What all the methods are implemented in the WCF service is implemented in the Contract.

49. What are Behavior and Bindings?
A. Binding mainly describes about the communication of the client and service. For this, there are protocols corresponding to the binding behavior which will take care of the communication channel. There are different protocols which we use for the different types of bindings. E.g. HTTP, TCP, MSMQ, Named Pipes etc.
Behavior is used for the common configurations that could be for endpoints. When we use the common behavior, they affect to all the end points. Adding the service behavior affect the service related stuff while the endpoint related behavior affects the end points. Also operations level behavior affects the operations.

50. What are different types of Contracts supported?
A. There are mainly 5 type of contracts used in WCF service:
a. Service Contract
b. Operation Contract
c. Data Contract
d. Message Contract
e. Fault Contract

51. What is the difference between Transport and Message Security mode?
A. WCF supports 2 types of security- Transport Level Security and Message Level Security
Transport Level Security- In this type of security, we make the transport channel as secure so that the data flows in that channel will be automatically secured. For HTTP channel, we use the client certificate for the security of the web address. SSL is used for the HTTP channel security. As we don’t need to secure each of the messages which are floating between the client and the service, the speed is faster as direct message is going to the client from the service.
Message level security- This type of security in WCF is used where we don't have the fixed transport medium and we need to secure each message which is floating between the server and the client. In this type of security we use certain algorithms for making the message as secure message. We use some extra bits and send with the message. We also use some encryption techniques like SHA1 or MD5 which make the proper security for our message. As each message needs to be secured, this type of security makes some delay in the process of sending and receiving the messages.

52. How to configure WCF security to support Windows authentication?
A. To support the WCF security in Windows Authentication, we need to add the ClientCredetialType attribute to “Windows” under the security tab element:
transport clientCredentialType="Windows"

53. How to use Fault Contract?
A.  Fault Contract is mainly used for viewing and displaying the errors which occurred in the service. So it basically documents the error and the error message can be shown to the user in the understandable way. We can’t use here the try….catch block for the error handling because the try…catch is the technology specific (.Net Technology). If we use the try...catch block for handling the errors, the error will not be reached to the client who is consuming the service. Because this error will not be included in the message. So we use the Fault contract for the error handling.
e.g. To use the Fault contract, we can simply write like the below:
public  int Add(int number1,int number2)
  // write some implementation
 throw new FaultException (“Error while adding data..”);
Here the fault Exception method is the inbuilt method which will throw the exception and display the message . We can use the custom class so that the message can be customized and the customized message can be sent to the client.
So we can create  a clss like:
public Class CustomException
 public int ID {get;set;}
 public string Message {get;set;}
 public string Type{get;set;}
Now this custom type we can use with the Operation Contract as:
public interface IMyInterface
 int Add(int num1,int num2);
Now while implementation of the Add method, we can assign the class properties.


54. Diff between XML and XAML.
A. XAML is the declarative XML based language which is used to define the objects and properties. XAML document is loaded by XAML parser. So XAML Parser initiates the objects and set those properties. XAML is mainly used in creating the objects in WPF and Silverlight applications.
For more detailed explanation, you can go through the below link:

55. Stack Panel and Wrap Panel.
A. StackPanel is one of layout control in WPF. We can place the child controls inside the stackpanel either horizontally or vertically. So it provides two types of orientations- Horizontal Orientation and Vertical orientation.
You can go through the below link for more detailed explanation and the code snippet:

Wrap panel is another layout control which is similar to the StackPanel. Wrap panel not only keep the control in horizontal and vertical orientation but also wrap them into new line if there is no space. Here also the orientation can be set as Horizontal or Vertical. Its main use is to arrange the tabs in the tab control, menu control or in toolbar items.
You can go through the below link for more details:

56. Hierarchical Data Template.
A. Hierarchical Data Template is a type of data template which is used to bind the controls which  supports HeaderedItemsControl, like  TreeViewItem or MenuItem
We can bind those controls items using the Hierarchical Data Template. It displayed the data into Hierarchical structure in the tree structure. It could be in the left to right or top to bottom.
You can go through the below link for more details:

57. Virtualization.
A. This is the feature in WPF which increases the efficiency of the programs when there are the large data objects. If the WPF ItemsControl is bound with the large collection data source object and we enabled the virtualization, then the controls will show only the data which is in the visual container for those items which are visible currently. This visual data is only the small part of the large data object. Now when the user will scroll down or up, the rest of the data will be visible and previous data will be hidden again. So this is increase the efficiency of the program from the UI prospective.

58. Events and Routed Events.
A.  Routed event is special type of event which can invoke and handle multiple events from different objects rather than the event which is coming from one object. So it generally handles the object from the element tree. So whatever the elements inside the element tree and if they generate the event-may be multiple events, the routed event is capable of handling those events.
The routed event can be invoked in both the directions but in general it comes from the source element and then bubbled up in the element tree until the root element.

59. Bubbling and Tunneling.
A. Bubbling: When the events are raised form the innermost element in the visual tree and comes up towards the root element, is called as bubbling.
Tunneling: It is the opposite process of Bubbling where the events fired by the root element goes down towards the last child element control.
Please go through the below link for more details:

60. Resource Dictionary, Static Resources and Dynamic Resources.
A. Static and Dynamic resources are used for binding the resources to the control objects.
The main difference between StaticResource and DynamicResource is that how the resource is retrieved elements. If the resource is StaticResource, it will be retrieved only once by the element who is referencing it  and it will be used for all the resources. While the DynamicResource gets its value each time they reference to the objects. So StaticResource is faster than the DynamicResource , because StaticResource needs to get the value only once while the DynamicResource needs each time.

61. What is Prism?
A. Prism is the framework or the set of guidelines which is used to develop the WPF desktop application as well as the Silverlight Rich Internet applications. So it’s a kind of Design pattern to Develop the XMAL based application. It also used to develop the Windows 7 applications. Prism mainly helps to design the loosely coupled components which can be easily integrated with the other components of the overall application. Prism mainly used to build the composite applications which need various other components to be integrated.
Prism mainly guides of creating the applications using the Model-View-ViewModel (MVVM) model, Managed Extensibility Framework (MEF), and navigation in the application.
To use the Prism framework, we need to use their library called as Prism Library. So prism Library is the inbuilt set of components which can be used in developing the WPF and Silverlight applications.
You can go through the below link for more details and the use of the components of the Prism framework:

62. Dependency Injection, Event Aggregator.
A. For the details about the dependency injection, you can follow the below link:
EventAggregator : It is the utility service which contains the events and allows the decouple the publisher and subscriber so that they can be buildup independently. Decouple is primarily useful when a new module needs to be added or removed or modified. The new module can be added as per the event fired and defined in the shell.
For more details about the Event Aggregator, you can follow the below link:

63. Shell, Bootstrapper and Region Managers
A. Bootstrapper:- An utility in WPF engine which is mainly responsible for the initialization of the application by using the composite application library. By using the bootstrapper we can find out how the components of the application are wired up in the composite application library. The bootstrapper responsibility to create the Shell or main window. Composite application library has the default abstract class UnityBootstrapper which actually handles the initialization.
You can go through the below link for more details about the bootstrapper:
Region and Region Managers: This is concept of Prism framework. We define the region through XAML code and once a region is defined, automatically it will be registered with the RegionManager. Actually the Bootstrapper registers a service called the RegionManager at run time. RegionManager is a dictionary where the key is name of the region. The value of the key is the reference of the IRegion interface. RegionAdapter is used to create the instance reference of the IRegion interface.
You can go through the below link for more details about the Region and Region Manager:

64. What are MEF and Unity?
A.  The MEF (Managed Extensibility Framework) is the new concept in .Net 4.0. It is used to create the lightweight and extensible applications to create Managed Extensibility Framework. It is not only allows the extension but also reused within the application. Extension can be easily encapsulating the code using the MEF.
For more details, you can go through the below link:

65. How to navigate to another page?
A. There is a class NavigationService which can be used for navigation of the WPF window:

Hope the answer will be helpful to all the members.