asp.net interview questions

ASP.NET
Interview Questions

This
is a list of questions I have gathered and created over a period of
time from my experience, many of which I felt where incomplete
or simply wrong.  I have finally taken the time to go through
each question and correct them to the best of my ability. 
However, please feel free to post feedback to challenge, improve, or
suggest new questions.  I want to thank those of you that have
contributed quality questions and corrections thus far.

There
are some questions in this list that I do not consider to be good
questions for an interview.  However, they do exist on other
lists available on the Internet so I felt compelled to keep them here
for easy access.

1. 
   Describe
   the role of inetinfo.exe, aspnet_isapi.dll andaspnet_wp.exe
   in the page loading process.
   inetinfo.exe is theMicrosoft IIS
   server running, handling ASP.NET requests among other things.When an
   ASP.NET request is received (usually a file with .aspx extension),
   the ISAPI filter aspnet_isapi.dll takes care of it by passing the
   request tothe actual worker process aspnet_wp.exe.
    

   
   

2. 
   What’s
   the difference between Response.Write()
   andResponse.Output.Write()?
   Response.Output.Write() allows
   you to write formatted output. 
    
   

   
   

3. 
   What
   methods are fired during the page load?
   Init() - when the
   page is instantiated
   Load() - when the page is loaded into server
   memory
   PreRender() - the brief moment before the page is
   displayed to the user as HTML
   Unload() - when page finishes
   loading. 
    
   

   
   

4. 
   When
   during the page processing cycle is ViewState available?
   After
   the Init() and before the Page_Load(), or OnLoad() for a control. 
    
   
   

   
   

5. 
   What
   namespace does the Web page belong in the .NET Framework class
   hierarchy?
   System.Web.UI.Page 
    
   

   
   

6. 
   Where
   do you store the information about the user’s
   locale?
   System.Web.UI.Page.Culture 
    
   

   
   

7. 
   What’s
   the difference between Codebehind="MyCode.aspx.cs"
   andSrc="MyCode.aspx.cs"?
   CodeBehind is relevant to
   Visual Studio.NET only. 
    
   

   
   

8. 
   What’s
   a bubbled event?
   When you have a complex control, like
   DataGrid, writing an event processing routine for each object (cell,
   button, row, etc.) is quite tedious. The controls can bubble up
   their eventhandlers, allowing the main DataGrid event handler to
   take care of its constituents. 
    
   

   
   

9. 
   Suppose
   you want a certain ASP.NET function executed on MouseOver for
   a certain button.  Where do you add an event handler?
   Add
   an OnMouseOver attribute to the button.  Example:
   btnSubmit.Attributes.Add("onmouseover","someClientCodeHere();"); 
    
   
   

   
   

10. 
    What
    data types do the RangeValidator control support?
    Integer,
    String, and Date. 
     
    

    
    

11. 
    Explain
    the differences between Server-side and Client-side
    code?
    Server-side code executes on the server. 
    Client-side code executes in the client's browser. 
     
    
    

    
    

12. 
    What
    type of code (server or client) is found in a Code-Behind class?
    The
    answer is server-side code since code-behind is executed on the
    server.  However, during the code-behind's execution on the
    server, it can render client-side code such as JavaScript
    to be processed in the clients browser.  But just to
    be clear, code-behind executes on the server, thus making it
    server-side code. 
     
    

    
    

13. 
    Should
    user input data validation occur server-side or client-side?
     Why?
    All user input data validation should occur on the
    server at a minimum.  Additionally, client-side validation can
    be performed where deemed appropriate and feasable to provide a
    richer, more responsive experience for the user. 
     
    

    
    

14. 
    What
    is the difference between Server.Transfer and Response.Redirect?
     Why would I choose one over the other?
    Server.Transfer
    transfers page processing from one page directly to the
    next page without making a round-trip back to the client's browser. 
    This provides a faster response with a little less overhead on the
    server.  Server.Transfer does not update the clients url
    history list or current url.  Response.Redirect is used to
    redirect the user's browser to another page or site.  This
    performas a trip back to the client where the client's browser is
    redirected to the new page.  The user's browser history list is
    updated to reflect the new address. 
     
    

    
    

15. 
    Can
    you explain the difference between an ADO.NET Dataset and an ADO
    Recordset?
    Valid answers are:
    ·  A DataSet can
    represent an entire relational database in memory, complete with
    tables, relations, and views.
    ·  A DataSet is
    designed to work without any continuing connection to the original
    data source.
    ·  Data in a DataSet is bulk-loaded,
    rather than being loaded on demand.
    ·  There's no
    concept of cursor types in a DataSet.
    ·  DataSets
    have no current record pointer You can use For Each loops to move
    through the data.
    ·  You can store many edits in a
    DataSet, and write them to the original data source in a single
    operation.
    ·  Though the DataSet is universal, other
    objects in ADO.NET come in different versions for different data
    sources. 
     
    

    
    

16. 
    What
    is the Global.asax used for?
    The
    Global.asax (including the Global.asax.cs file) is used to implement
    application and session level events. 
     
    

    
    

17. 
    What are
    the Application_Start and Session_Start subroutines used for?
    This
    is where you can set the specific variables for the Application and
    Session objects. 
     
    

    
    

18. 
    Can
    you explain what inheritance is and an example of when you might use
    it?
    When you want to inherit (use the functionality of)
    another class.  Example: With a base class named Employee,
    a Manager class could be derived from the Employee base class. 
     
    
    

    
    

19. 
    Whats
    an assembly?
    Assemblies are the building blocks of the .NET
    framework.
    Overview of assemblies from MSDN 
     
    
    

    
    

20. 
    Describe
    the difference between inline and code behind.
    Inline code
    written along side the html in a page. Code-behind is code written
    in a separate file and referenced by the .aspx page. 
     
    
    

    
    

21. 
    Explain
    what a diffgram is, and a good use for one?
    The DiffGram is
    one of the two XML formats that you can use to render DataSet object
    contents to XML.  A good use is reading database data to
    an XML file to be sent to a Web Service. 
     
    

    
    

22. 
    Whats
    MSIL, and why should my developers need an appreciation of it if at
    all?
    MSIL is the Microsoft Intermediate Language. All .NET
    compatible languages will get converted to MSIL.  MSIL also
    allows the .NET Framework to JIT compile the assembly on the
    installed computer. 
     
    

    
    

23. 
    Which
    method do you invoke on the DataAdapter control to load your
    generated dataset with data?
    The Fill() method. 
     
    
    

    
    

24. 
    Can
    you edit data in the Repeater control?
    No, it just reads the
    information from its data source. 
     
    
    

    
    

25. 
    Which
    template must you provide, in order to display data in a Repeater
    control?
    ItemTemplate. 
     
    

    
    

26. 
    How
    can you provide an alternating color scheme in a Repeater
    control?
    Use the AlternatingItemTemplate. 
     
    
    

    
    

27. 
    What
    property must you set, and what method must you call in your code,
    in order to bind the data from a data source to the Repeater
    control?
    You must set the DataSource property and call the
    DataBind method. 
     
    

    
    

28. 
    What
    base class do all Web Forms inherit from?
    The Page class. 
     
    
    

    
    

29. 
    Name
    two properties common in every validation control?
    ControlToValidate
    property and Text property. 
     
    

    
    

30. 
    Which
    property on a Combo Box do you set with a column name, prior to
    setting the DataSource, to display data in the combo
    box?
    DataTextField property. 
     
    

    
    

31. 
    Which
    control would you use if you needed to make sure the values in two
    different controls matched?
    CompareValidator control. 
     
    
    

    
    

32. 
    How
    many classes can a single .NET DLL contain?
    It can contain
    many classes.
     

    
    

Custom Error Handling in C#

In C# we can handle custom errors by creating a CustomException class Which should be inherited by Exception class. Once the Custom Exception class is ready then in each code use try and catch block. In catch block throw a new exception for you CustomException class. In CustomException class we can write any code or logging information.

here is the Code snippet for Handling Custom Exception.

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

using ErrorHandling;

namespace ExceptionHandling

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

private void button1_Click(object sender, EventArgs e)

{

try

{

int a =GetValue();

}

catch (CustomException ex)

{

MessageBox.Show(ex.Message);

}



}

private int GetValue()

{

try

{

int a = 0;

int b = 4;

int z = (b / a);

return z;

}

catch (Exception ex)

{

throw new CustomException("Devide by zero is a custom Message");

}

}



}

}

namespace ErrorHandling

{

[global::System.Serializable]

public class CustomException : Exception

{

//

// For guidelines regarding the creation of new exception types, see

// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/cpconerrorraisinghandlingguidelines.asp

// and

// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dncscol/html/csharp07192001.asp

//

public CustomException() { }

public CustomException(string message) : base(message) { }

public CustomException(string message, Exception inner) : base(message, inner) { }

protected CustomException(

System.Runtime.Serialization.SerializationInfo info,

System.Runtime.Serialization.StreamingContext context)

: base(info, context) { }

}

}

Because we can not handle the custom Error at first level of handling. So this is work around of that. If any body find any such kind of option please add the comment in this article.

Web User control in ASP.NET with AJAX

This is a application which shows that how to get chat data from server without refreshing the page. here in this application i have used ASP.NET framework 1.1 and with XMLHttpRequest object. i have created a Ascx control which you can use for your application to put a chat box at any position of your page.

There could be a better solution for chat box in web application but i found it good.

Downloads

• Download source files - 8 Kb
• Download demo project - 42 Kb

How to use JSON in ASP.NET

JSON is JavaScript Object Notation. Which improve the code readability in java script code and also it help to create object code at client side in ASP.NET. Here you can define your properties and method.

Like

var VariableName=

{

“Property”: value, // Properties

“FunctionName1”:

function(){

//Function body.

},

“FunctionName2”:

function(){

//Function Body.

}

}

If we need any Customer object at client side then we can create like

Var CustomerJSON =

{

“Name”: “Mr Harry”,

“Age”: 23,

“Address”: “10000, Abc Blvd, Los Angeles”,

“Salary”: 300,

“IsRetired”:

function()

{

If (CustomerJSON.Age > 56)

return true;

}

}

You can directly add this JSON script in your ASP.NET page or you can register it by Register client script method of page.

Adding Java script in ASPNet page

Method -1 // In code behind (C# page)

Literal js = new Literal();

js.Text = "<script type='text/javascript' Src= 'CustomerJSON.js'></script>";

this.Header.Controls.Add(js);

Method -2 // in code behind (C# page)

StringBuilder sb = new StringBuilder();

sb.AppendLine("<script language=\"javascript\" type=\"text/javascript\">");

sb.AppendLine(Write your whole JSON code here.);

sb.AppendLine("</script>");

this.ClientScript.RegisterStartupScript(GetType(), "StartupScript", sb.ToString());

Method -3 // in aspx file

Add a new tag for

<script type='text/javascript' Src= 'CustomerJSON.js'></script>

Code Snippet for Page Heading Comments

Introduction

This article/code snippet is use full in managing your code properly. like every class file should contain any comment about auther ,created date and other things. This Article contain two code snippet one is C# and other one is Vb.Net.

Background

Code Snippet are just xml file which we are using in your coding to display predefine code.

Using the code

every coding file (.cs or .vb) should contain the information about auther,created by namespace and other things.

Copy the attached file for following Locations

.

Location for Vb Code Snippet:

C:\Program Files\Microsoft Visual Studio 8\VB\Snippets\1033\application

Location for C# Code Snippet:

C:\Program Files\Microsoft Visual Studio 8\VC#\Snippets\1033\Visual C#

How to use The Code snippet.

For VB.NET

go to your any .vb page and right click at the top line of page.

then click on Insert Snippet. --> Select Application --> Select "#PageHeader"

then write down all the values mentioned at Snippet literals.

For C#

go to your any .cs page and right click at the top line of page.

then click on Insert Snippet. --> Select Visual C# --> Select "#PageHeader"

then write down all the values mentioned at Snippet literals.

if you still find any problem then feel free to talk with me.

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