Net Interview Questions and Answers - IDCO

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					1.   What’s the difference between Response.Write() andResponse.Output.Write()?

     Response.Output.Write() allows you to write formatted output.

2.   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.

3.   When during the page processing cycle is ViewState available?

     After the Init() and before the Page_Load(), or OnLoad() for a control.

4.   What namespace does the Web page belong in the .NET Framework class hierarchy?


5.   Where do you store the information about the user’s locale?

     CodeBehind is relevant to Visual Studio.NET only.

6.   What’s the difference between Codebehind="MyCode.aspx.cs"


     CodeBehind is relevant to Visual Studio.NET only.

7.   What is the Global.asax used for?

     The Global.asax (including the Global.asax.cs file) is used to implement application and session level


8.   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.

9.   Whats an assembly?

     Assemblies are the building blocks of the .NET framework;
10. 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.

11. Which method do you invoke on the DataAdapter control to load your generated dataset

   with data?

   The Fill() method.

12. Can you edit data in the Repeater control?

   No, it just reads the information from its data source.

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


14. Name two properties common in every validation control?

   ControlToValidate property and Text property.

15. What base class do all Web Forms inherit from?

   The Page class.

16. 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

17. What is ViewState?

   ViewState allows the state of objects (serializable) to be stored in a hidden field on the page.

   ViewState is transported to the client and back to the server, and is not stored on the server or any
        other external source. ViewState is used the retain the state of server-side objects between


     18. What is the lifespan for items stored in ViewState?

        Item stored in ViewState exist for the life of the current page. This includes postbacks (to the same


     19. What does the "EnableViewState" property do? Why would I want it on or off?

        It allows the page to save the users input on a form across postbacks. It saves the server-side

        values for a given control into ViewState, which is stored as a hidden value on the page before

        sending the page to the clients browser. When the page is posted back to the server the server

        control is recreated with the state stored in viewstate.

     20. What are the different types of Session state management options available with


        ASP.NET provides In-Process and Out-of-Process state management. In-Process stores the session

        in memory on the web server. This requires the a "sticky-server" (or no load-balancing) so that the

        user is always reconnected to the same web server. Out-of-Process Session state management

        stores data in an external data source. The external data source may be either a SQL Server or a

        State Server service. Out-of-Process state management requires that all objects stored in session

        are serializable.

ASP.NET 3.5 Interview Questions & Answers :

1.       Explain            the     life      cycle        of      an        ASP        .NET           page.?
Following        are    the       events     occur      during      ASP.NET        Page      Life      Cycle:

6)Control                                                                                              Events

Among above events Page_Render is the only event which is raised by page. So we can't
write                     code                        for                      this                       event.

2.        how           does           the            cookies             work            in
we know Http is an state-less protocol which is required for interaction between clinet and
server                                                                                                          .

so there is an need to remeber state of request raised by an web browser so that
web      server can     recognize      you        have       already      previously   visited       or     not.

There          are            two            types             of state          management techniques:
a)                        Client                             side state                        management
b)                   Server                   -                    side                   statemanagement

Using cookies comes under clinet side statemanagement .In HttpResponse we write
Cookie       containing          sessionId         and         other        information        within         it.

when a browser made a request to the web server the same cookie is sent to the server
where server recognize the session id and get other information stored to it previously.

3.    What    is     Ispostback      method          in     ASP.Net?      Why     do   we      use        that??
Basically Post back is an action performed by a interactive Webpage. When it goes to the
server side for a non-client Operation Server again posts it back to the client and hence the

will not allow the page to post back again n again bcoz it reduces the performance.

4.           Can           User                  Control               be            stored              in           library?.
I                                   will                                           say                                        "NO"

there                  are                        3                      types                    of                      controls:
1)                                                          User                                                           Control
2)                                                        Custom                                                           Control
3)                                                           Web                                                             parts

you can reuse User control in the current project in which you have built it, but you can't
move it to other project as unless you just copy paste the same file there and make the
changes        for     that      project              (     which        violets      the         concept       of        library).

but custom control can be shared between projects. and you can precompile them even as a
dll,    so     this     means           you           can      use        them       in     library       of      any        type.

5.     what     is     the      difference                between           application       state         and       caching?
Application Object and Cached Object both falls under Server side State Management.

Application object        resides      in    InProc         i.e.    on    the    same       server      where        we     hosted
our application.
Cache         Object          resides            on         server           side/         DownStream/Client                 Side.

Application Object              will              be               disposed           once application will                  stop.
Cache        Object     can       be        disposed           using         Time         based        cache      dependency.

Only one user can access Application Object at a time hence we have to lock it every time
we                                                            modify                                                            it.

6.                 what                     is                     boxing                   and                      unboxing?
Boxing is what happens when a value-type object is assigned to a reference-type variable.
Unboxing is what happens when a reference-type variable is assigned to a value-type

7.          What                are                the            uses             of                Reflection??
Reflection is            a            concept               using              which            we               can

1)                           Load                            assemblies                                  dynamically
2)                                          Invoke methods at                                                runtime
3)              Retriving                 type               information                 at                 runtime.

8.      What            is          the          use        of       AutoWireup                in 
AutoEventWireup attribute is used to set whether the events needs to be automatically
generated                                                   or                                                   not.
In the case where AutoEventWireup attribute is set to false (by default) event handlers are
automatically required for Page_Load or Page_Init. However when we set the value of the
AutoEventWireup attribute to true the ASP.NET runtime does not require events to specify
event             handlers                  like             Page_Load                  or                 Page_Init.

9.      what        events           will          occur      when         a       page             is      loaded?
Below             are               the events occures               during                   page              load.

1)                                                                                                       Page_PreInit
2)                                                                                                          Page_Init
3)                                                                                            Page_InitComplete
4)                                                                                                   Page_PreLoad

10.         Where              is           the            View          state           Data                stored?
ViewState data is stored in the hidden field. When the page is submitted to the server the
data is sent to the server in the form of hidden fields for each control. If th viewstate of the
control is enable true the value is retained on the post back to the client when the page is
post                                                                                                                        backed.

11. What is the difference between custom web user control and a custom web
server                                                                                                                     control?
Web                                                          User                                                           Control:
1)                                    Easy                                            to                                     Create.
2) It Can be used inside the same Application.(To use it in other application we need to add
it                                    to                                           that                                     project.)
3)          It           Can           take                 advantage                 of             Caching              Technique.

Web                                                         Server                                                          Control:
1)       Bit         tuff        to          create               as          compare                to       User          Control.
2)                                     Easy                                                 to                                    use.
3)                   Can                        be                       added                        to                    ToolBox.

12. Where do the Cookie State and Session State information be stored?
Cookie      Information        will    be       stored       in     a       txt    file     on   client      system       under     a
folder named Cookies. Search for it in your system you will find it.

Coming                                     to                                        Session                                   State

As we know for every process some default space will be allocated by OS.

In   case      of   InProc     Session          Info   will       be     stored       inside     the       process    where       our
application                                                         is                                                      running.
In case of StateServer Session Info will be stored using ASP.NET State Service.
In   case    of     SQLServer         Session        info    will      be    stored         inside   Database.       Default      DB
which will be created after running InstallSQLState Script is ASPState.

13. What is the difference between adding reference in solution Explorer and
adding                         references                                   by                        USING                          ?
Adding reference in solution explorer is used to add the DLL for that project for reference
only. If you want to utilize that DLL methods/functions in our aspx.cs/.cs file etc you must
write            using          that                 nameclass                    library            name            in           file.
14.     What    are      the    different      types      of     sessions    in   ASP.Net?          Name      them.?
Session Management can                      be             achieved               in              two             ways


OutProc                         is                       again                         two                        types
1)State                                                                                                          Server
2)SQL                                                                                                            Server

1)    Faster     as      session       resides     in      the     same     process          as     the    application
2) No need to serialize the data

1) Will degrade the performance of the application if large chunk of data is stored
2) On restart of IIS all the Session info will be lost

State                                                                                                         Server
1)                    Faster                       then SQL                       Server session management
2)             Safer                 then               InProc.             As                IIS             restart
won't effect the session data

1)                Data                      need                   to                  be                   serialized
2)      On     restart     of        ASP.NET       State       Service      session      info       will    be     lost
3)Slower as compared to InProc

SQL                                                                                                           Server
1)                               Reliable                                    and                                 Durable
2)               IIS                   and                    ASP.NET                     State                  Service
restart                won't                  effect                  the                     session                data
3) Good place for storing large chunk of data

1)                   Data                    need                  to                      be                   serialized
2)        Slower            as        compare             to        InProc           and              State       Server
3)Need                                to                            purchase                                    Licensed
version                                                   of SQL                                                   Serve
15. How do you design a website with multilingual support in ASP.NET?
Multilingual website can be created using Globalization and Localization.

Using Globalization we change the Currency Date Numbers etc to Language Specific Format.

To change the string which is there in the label button etc to language specific string we use

In Localization we have to create different Resource files for different languages.
During this process we use some classes present in System.Resources System.Globalization
System.Threading                                                                                             namespaces.
16.   What      is     caching?       What         are    different      ways       of    caching       in    ASP.NET?
Caching is a technique of persisting the data in memory for immediate access to requesting
program calls. This is considered as the best way to enhance the performance of the

Caching is                                   of                                 3                                  types:
Output Caching -                       Caches                      the                        whole                 page.
Fragment Caching -                 Caches                 a           part               of            the          page
Data Caching -                                Caches                                 the                             data

17.            What              is               meant             by              3-tier               architecture.
We                 generally                      split             our application into                        3-Layers
1)Presentation Layer ( Where we keep all web forms Master Pages and User Controls).
2)Business Layer (Where we keep business logic). e.g Code related to manipulating data
Custom Exception classes Custom Control classes Login related code if any etc. etc.
3)Data Access Layer (Where we keep code used to interact with DB). e.g. We can have the
methods which are using SQL Helper (Application Block).

18.      Explain      the      basic       functionality     of         garbage       collector?
Garbage Collector in .Net Framework is used for Automatic Memory Management i.e. it is
collect all unused memory area and give to application. system.gc.collect() is a method for
release the memory. But remember one think it is only an request i.e. we can't explicitly
release the memory by using system.gc.collect().

19.   What      is   the    difference    between    mechine.config        and      web.config?
machine.config is a system level configuration i.e it is applied on all application in o/s that
the configuration is set where as in web.config it is applicable to only one application i.e
each webapplication will contain atleast on web.config file.

20.   How      can   exception    be     handled   with    out    the    use   of   try   catch?
using Exception Management application block

Application_error objects

21. What is the difference between Response.Redirect and Server.Transfer.
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 toredirect the user's browser to another page or site. This
performs 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.
22.       Where            the            assembly                  is         stored               in
private are stored in application / bin directory and public are stored in GAC.

23. How we implement Web farm and Web Garden concept in ASP.NET?.
A web farm is a multi-server scenario. So we may have a server in each state of US. If the
load on one server is in excess then the other servers step in to bear the brunt.
How        they           bear           it          is           based            on           various           models.
1.        RoundRobin.                  (All               servers             share                load           equally)
2.                                              NLB                                                           (economical)
3.     HLB        (expensive            but       can             scale        up       to             8192       servers)
4.                Hybrid                       (of                        2                        and                  3).
5.                 CLB                        (Component                             load                       balancer).
A web garden is a multi-processor setup. i.e. a single server (not like the multi server
How               to                  implement                      webfarms                        in              .Net:
Go                               to                                      web.config                                    and
Here             for             mode                      you                have                  4             options.
a) Say mode inproc (non web farm but fast when you have very few customers).
b)             Say                mode                      StateServer                     (for                 webfarm)
c)             Say                mode                       SqlServer                      (for                 webfarm)
Whether to use option b or c depends on situation. StateServer is faster but SqlServer is
more         reliable       and           used              for          mission            critical          applications.
How                  to                use                        webgardens                        in               .Net:
Go                               to                                      web.config                                    and
Change the false to true. You have one more attribute that is related to webgarden in the
same tag called cpuMask.

24. Is there any limit for query string? means what is the maximum size?..
Servers should be cautious about depending on URI lengths above 255 bytes because some
older client or proxy implementations may not properly support these lengths.
Query         string length           depends           on      browser          compatability

IE                         supports                           upto                           255
Firefox supports upto 4000

25.      What        is       the      exact        purpose      of       http      handlers?
ASP.NET maps HTTP requests to HttpHandlers. Each HttpHandler enables processing of
individual HTTP URLs or groups of URL extensions within an application. HttpHandlers have
the same functionality as ISAPI extensions with a much simpler programming model

1.Default   HttpHandler   for   all   ASP.NET   pages    ->ASP.NET    Page   Handler   (*.aspx)
2.Default HttpHandler for all ASP.NET service pages->ASP.NET Service Handler (*.asmx)

An HttpHandler can be either synchronous or asynchronous. A synchronous handler does
not return until it finishes processing the HTTP request for which it is called. An
asynchronous handler usually launches a process that can be lengthy and returns before
that                                      process                                         finishes
After writing and compiling the code to implement an HttpHandler you must register the
handler using your application's Web.config file.

.Net Interview Questions and Answers
What is .NET?
.NET is essentially a framework for software development. It is similar in nature to any
other software development framework (J2EE etc) in that it provides a set of runtime
containers/capabilities, and a rich set of pre-built functionality in the form of class
libraries and APIs
The .NET Framework is an environment for building, deploying, and running Web Services
and other applications. It consists of three main parts: the Common Language Runtime,
the Framework classes, and ASP.NET.
How many languages .NET is supporting now?
When .NET was introduced it came with several languages. VB.NET, C#, COBOL and Perl,
etc. The site DotNetLanguages.Net says 44 languages are supported.

How is .NET able to support multiple languages?
A language should comply with the Common Language Runtime standard to become a
.NET language. In .NET, code is compiled to Microsoft Intermediate Language (MSIL for
short). This is called as Managed Code. This Managed code is run in .NET environment. So
after compilation to this IL the language is not a barrier. A code can call or use a function
written in another language.

How ASP .NET different from ASP?
Scripting is separated from the HTML, Code is compiled as a DLL, these DLLs can be
executed on the server.

What is smart navigation?
The cursor position is maintained when the page gets refreshed due to the server side
validation and the page gets refreshed.

What is view state?
The web is stateless. But in ASP.NET, the state of a page is maintained in the in the page
itself automatically. How? The values are encrypted and saved in hidden controls. this is
done automatically by the ASP.NET. This can be switched off / on for a single control

How do you validate the controls in an ASP .NET page?
Using special validation controls that are meant for this. We have Range Validator, Email

Can the validation be done in the server side? Or this can be done only in the
Client side?

Client side is done by default. Server side validation is also possible. We can switch off the
client side and server side can be done.

How to manage pagination in a page?
Using pagination option in DataGrid control. We have to set the number of records for a
page, then it takes care of pagination by itself.
What is ADO .NET and what is difference between ADO and ADO.NET?
ADO.NET is stateless mechanism. I can treat the ADO.Net as a separate in-memory
database where in I can use relationships between the tables and select insert and
updates to the database. I can update the actual database as a batch.

Observations between VB.NET and VC#.NET?
Choosing a programming language depends on your language experience and the scope of
the application you are building. While small applications are often created using only one
language, it is not uncommon to develop large applications using multiple languages.

For example, if you are extending an application with existing XML Web services, you
might use a scripting language with little or no programming effort. For client-server
applications, you would probably choose the single language you are most comfortable
with for the entire application. For new enterprise applications, where large teams of
developers create components and services for deployment across multiple remote sites,
the best choice might be to use several languages depending on developer skills and long-
term maintenance expectations.

The .NET Platform programming languages - including Visual Basic .NET, Visual C#, and
Visual C++ with managed extensions, and many other programming languages from
various vendors - use .NET Framework services and features through a common set of
unified classes. The .NET unified classes provide a consistent method of accessing the
platform's functionality. If you learn to use the class library, you will find that all tasks
follow the same uniform architecture. You no longer need to learn and master different API
architectures to write your applications.

In most situations, you can effectively use all of the Microsoft programming languages.
Nevertheless, each programming language has its relative strengths and you will want to
understand the features unique to each language. The following sections will help you
choose the right programming language for your application.

Visual Basic .NET
Visual Basic .NET is the next generation of the Visual Basic language from Microsoft. With
Visual Basic you can build .NET applications, including Web services and ASP.NET Web
applications, quickly and easily. Applications made with Visual Basic are built on the
services of the common language runtime and take advantage of the .NET Framework.
Visual Basic has many new and improved features such as inheritance, interfaces, and
overloading that make it a powerful object-oriented programming language. Other new
language features include free threading and structured exception handling. Visual Basic
fully integrates the .NET Framework and the common language runtime, which together
provide language interoperability, garbage collection, enhanced security, and improved
versioning support. A Visual Basic support single inheritance and creates Microsoft
intermediate language (MSIL) as input to native code compilers.

Visual Basic is comparatively easy to learn and use, and Visual Basic has become the
programming language of choice for hundreds of thousands of developers over the past
decade. An understanding of Visual Basic can be leveraged in a variety of ways, such as
writing macros in Visual Studio and providing programmability in applications such as
Microsoft Excel, Access, and Word.

Visual Basic provides prototypes of some common project types, including:
• Windows Application.
• Class Library.
• Windows Control Library.
• ASP.NET Web Application.
• ASP.NET Web Service.
• Web Control Library.
• Console Application.
• Windows Service.
• Windows Service.
Visual C# .NET

Visual C# (pronounced C sharp) is designed to be a fast and easy way to create .NET
applications, including Web services and ASP.NET Web applications. Applications written
in Visual C# are built on the services of the common language runtime and take full
advantage of the .NET Framework.

C# is a simple, elegant, type-safe, object-oriented language recently developed by Microsoft
for building a wide range of applications. Anyone familiar with C and similar languages
will find few problems in adapting to C#. C# is designed to bring rapid development to the
C++ programmer without sacrificing the power and control that are a hallmark of C and
C++. Because of this heritage, C# has a high degree of fidelity with C and C++, and
developers familiar with these languages can quickly become productive in C#. C#
provides intrinsic code trust mechanisms for a high level of security, garbage collection,
and type safety. C# supports single inheritance and creates Microsoft intermediate
language (MSIL) as input to native code compilers.

C# is fully integrated with the .NET Framework and the common language runtime, which
together provide language interoperability, garbage collection, enhanced security, and
improved versioning support. C# simplifies and modernizes some of the more complex
aspects of C and C++, notably namespaces, classes, enumerations, overloading, and
structured exception handling. C# also eliminates C and C++ features such as macros,
multiple inheritance, and virtual base classes. For current C++ developers, C# provides a
powerful, high-productivity language alternative.

Visual C# provides prototypes of some common project types, including:
• Windows Application.
• Class Library.
• Windows Control Library.
• ASP.NET Web Application.
• ASP.NET Web Service.
• Web Control Library.
• Console Application.
• Windows Service.