Asp.net interview, .NET Interview Questions and Answers,
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interview questions and answers, IIS interview questions and answers, sql
server interview questions and answers, vb.net interview questions and answers,
XML interview questions and answers, Asp.Net 3.5,Asp.Net 4.0,Asp.Net4.5,
Asp.Net C#, VB.Net.
Tricky Questions
1. If I’m developing an application that must accommodate
multiple security levels though secure login and my ASP.NET web application is
spanned across three web-servers (using round-robin load balancing) what would
be the best approach to maintain login-in state for the users?
Answer: You can use the security state maintained using a
database. (Use Authentication mode as database)
2. What’s the difference between Code
behind=”MyCode.aspx.cs” and src=”MyCode.aspx.cs” mce_src=”MyCode.aspx.cs”?
Answer: Visual Studio uses the Code behind attribute to
distinguish the page source or programming logic from the design. Also the src
attribute will make the page compile on every request. That is the page will
not be compiled in advance and stored in the bin as a dll instead it will be
compiled at run time.
3. Suppose you want a certain ASP.NET function executed on
Mouse Over over a certain button or textbox. Where do you add an event handler?
Answer: Every web control has an ability to add the
attributes on client side which will execute on client side and run a client
side script like a JavaScript function.
btnSubmit.Attributes.Add (“onMouseOver”,”someClientCode ()
;”) //For on mouse over of a button
TextBox1.Attributes.Add(“onFocus”,“ClearText();”) //For on
focus of a text box
4. Explain what a diffgram is and a good use for one?
Answer: The DiffGram is one of the two XML formats that you
can use to render Dataset object contents to XML. For reading database data to
an XML file to be sent to a Web Service.
5. What base class do all Web Forms inherit from?
Answer: The Page class.
6. Name two properties common in every validation control?
Answer: ControlToValidate and Text property.
7. What tags do you need to add within the Data grid tags to
bind columns manually?
Answer: Set AutoGenerateColumns Property to false on the
Data grid tag
8. What tag do you use to add a hyperlink column to the Data
Grid?
Answer: asp: HyperLinkColumn
9. What is the transport protocol you use to call a Web
service?
Answer: SOAP (Simple Object Access Protocol) is the
preferred protocol.
10. Where on the Internet would you look for Web services?
Answer: http://www.uddi.org
11. Which control would you use if you needed to make sure
the values in two different controls matched?
Answer: CompareValidator Control
12. What are the assembly entry points? An Assembly can have
how many entry points at a time?
Answer: An assembly can have only one entry point from
DllMain, Win Main or Main.
13. What does an assembly contain?
Answer:
• Manifest – The metadata describing the information below.
• Assembly name – Aids in versioning and visibility scope.
• Version information – The version number is integrated
into the assembly’s identity.
• Types – Boundaries and scopes of methods, classes,
properties, events, attributes.
• Locale – Information describing language/culture.
• Cryptographic Hash – Public key encoded hash acting as
version/security check.
• Security Permissions – The permissions within the assembly
determine the permissions that can be granted for all aspects of the assembly
contents.
14. What does an assembly manifest contains?
Answer: It contains assembly name, version number
(major.minor.build.revision) and culture Information. It also specifies the
strong name information, which is useful for shared assemblies, and list of
files, an assembly contains. It also provides information for type references
in an assembly and other referenced assemblies.
15. Which tool is used to deploy an assembly, so as the
assembly is available to all the application?
Answer: The GacUtil.exe is the tool, which allows us to add
any assembly to the windows GAC.
16. How many catch statements can be associated with single
try statement?
Answer: There can be a zero or more catch statement for each
try statement. So it has not limit to the number of catch statement per try statement.
17. What is Console and System a Class/a Data Member/a
routine/a namespace or a type?
Answer: Console is a class and System is namespace.
18. How many values can be returned from a method in C#?
Answer: Only one value can be returned from method, however
you can use ref or out variable to change more than one value in called method.
19. How to declare a variable named this in C#, with data
type string?
Answer: string @this;
20. Can we change the dimension of Array at run time like
Array [3, 4]?
Answer: Yes, We can change only the first position of array
dimension.
21. What keyword is used to accept a variable number of
parameter in a method?
Answer: “params” keyword is used as to accept variable
number of parameters.
22. What is a Namespace? What is the use of a namespace?
Answer: Namespaces are logical grouping of classes and other
types in hierarchical structure. Namespaces are useful to avoid collision or
ambiguity among the classes and type names. Another use of the namespace is to
arrange a group of classes for a specific purpose.
23. What does a keyword using works for?
Answer: Using is just a convention or a short-cut method
which allows us to access the classes in a namespace by referencing it once. So
whenever we want use the classes or methods in them, we can avoid typing the
entire namespace hierarchy. However it is not a good practice when there are
likely chances to have name ambiguity or collision of class names.
24. What is Enums in C#?
Answer: Enums or Enumerators are used to declare a set of
related constants (default start with 0); they are only available with
primitive data types like int and short etc.
25. What is Delegates?
Answer: Delegates are a type-safe, object-oriented
implementation of function pointers and are used in many situations where a
component needs to call back to the component that is using it. Delegates are
generally used as basis of events, which allow any delegate to easily be
registered for as event.
26. Which are the namespaces that are imported automatically
by Visual Studio in ASP.Net?
Answer: There are 7 namespaces which are imported
automatically.
1.
System
2.
System. Collections
3.
System.IO
4.
System.web
5.
System.web.UI
6.
System.web.UI.HTMLControls
7.
System.web.UI.WebControls
27. Which namespaces are used for data access?
1.
System. Data
2.
System.Data.OleDB
3.
System.Data.SQLClient
28. What do you mean by boxing and un-boxing?
Answer: C# provides us with Value types and Reference Types.
Value Types are stored on the stack and Reference types are stored on the heap.
The conversion of value type to reference type is known as boxing and
converting reference type back to the value type is known as un-boxing.
e.g.
int x = 10;
object o = x ; // Implicit boxing
object o = (object) x; // Explicit Boxing
x = o; // Implicit Un-Boxing
x = (int)o; // Explicit Un-Boxing
29. What are the different methods available under
sqlcommand class to access the data?
1.
ExecuteReader –Used where one or more records
are returned – SELECT Query.
2.
ExecuteNonQuery – Used where it affects a state
of the table and no data is being queried – INSERT, UPDATE, DELETE, CREATE and
SET queries.
3.
ExecuteScalar – Used where it returns a single
record(a single value normally) – SQL Functions like MIN(), NAX()
30. What are the different types of Session state management
options available with ASP.NET?
Answer: ASP.NET provides In-Process & Out-of-Process
state management,
Also known as “In-Proc” and “Out-Proc”. In-Proc stores the
session in memory of the web server, that is on the same server the ASP.Net
page is.
On the other hand Out-Proc session state management stores
the session data on external data source, which can be a SQL Server or Server
State Service. Out-of-Process state management requires the objects stored in
session, must be serializable.
31. What is Remoting? Give Example.
Answer: Remoting is a means by which one operating system
process, or program, can communicate with another process. The two processes
can exist on the same computer or on two computers connected by a LAN or the
Internet. Web services are probably the best known type of remoting, but they
are not the only option.
32. What is Marshalling?
Answer: Marshaling is a process of making an object in one
process (the server) available to another process (the client). There are two
ways to achieve the marshalling.
i. Marshal by value: the server creates a copy of the object
passes the copy to the client. When a client makes a call to an object
marshaled by value (MBV), the server creates an exact copy and sends that copy
to the client. The client can then use the object’s data and executable
functionality directly within its own process or application domain without
making additional calls to the server. Objects that the application accesses
frequently are best remoted using MBV.
ii. Marshal by reference: the client creates a proxy for the
object and then uses the proxy to access the object. When a client makes a call
to an object marshaled by reference (MBR), the .NET framework creates a proxy
in the client’s application domain and the client uses that proxy to access the
original object on the server. Large objects that the application accesses
relatively infrequently are good candidates for MBR.
33. What is a Static class? What are its features?
Answer: Static class is a class which can be used or
accessed without creating an instance of the class.
Important Features:
1.
Static class only contains static members and a
private constructor.
2.
Static class cannot be instantiated.
3.
Static classes are sealed by default and
therefore cannot be inherited.
34. What is sealed class? What are its features?
Answer: Sealed classes are those classes which can not be
inherited and thus any sealed class member can not be derived in any other
class. A sealed class cannot also be an abstract class.
In C# structs are implicitly sealed; therefore, they cannot
be inherited.
35. Can we declare a method as sealed?
Answer: In C# a method can’t be declared as sealed. However
when we override a method in a derived class, we can declare the overridden
method as sealed. By declaring it as sealed, we can avoid further overriding of
this method.
E.g.
Using System;
Class MyClass1
{
Public int x;
Public int y;
Public virtual void Method () {
Console.WriteLine (“virtual method”) ;}
}
Class My Class: MyClass1
{
Public override sealed void Method () {
Console.WriteLine (“sealed method”) ;}
}
Class Main Class
{Public static void Main () {
MyClass1 mC = new My Class ();
mC.x = 110;
mC.y = 150;
Console.WriteLine (“x = {0}, y = {1}”, mC.x, mC.y);
mC.Method () ;}
}
36. What is a Dataset?
Answer: A Dataset is an in memory representation of data
loaded from any data source.
37. What is a Data Table?
Answer: A Data Table is a class in .NET Framework and in
simple words a Data Table object represents a table from a database.
38. If you want to view an Assembly how to you go about it?
What is ILDASM?
Answer: You can use the MSIL Disassembler (Ildasm.exe) to
view Microsoft intermediate language (MSIL) information in a file. If the file
being examined is an assembly, this information can include the assembly’s
attributes, as well as references to other modules and assemblies. This
information can be helpful in determining whether a file is an assembly or part
of an assembly, and whether the file has references to other modules or
assemblies.
39. Where is version information stored of an assembly?
Answer: The version number is stored in the assembly
manifest along with other identity information, including the assembly name and
public key, as well as information on relationships and identities of other
assemblies connected with the application.
40. Is versioning applicable to private assemblies?
Answer: No
41. How to create a shared assembly or add an assembly to
GAC?
Answer: There are several ways an assembly can be added to
GAC.
1.
Use .msi installer designed to work with the
global assembly cache.
2.
Use GACUtil.exe provided by the .NET Framework
SDK.
3.
Use Windows Explorer to drag assemblies into the
cache.
43. What is reflection?
Answer: All .NET compilers produce metadata about the types
defined in the modules they produce. This metadata is packaged along with the
module (modules in turn are packaged together in assemblies), and can be
accessed by a mechanism called reflection. The System. Reflection namespace
contains classes that can be used to interrogate the types for a
module/assembly. Reflection is ability to find information about types
contained in an assembly at run time.
44. How can I produce an assembly?
Answer: Simply compile your class/module with the following
command.
C#.Net – CSC /t: library yourclassname.cs
VB.Net – VBC /t: library yourmodulename.vb
45. What is an Application Domain? How they get created?
Answer: An Application Domain can be thought of as a
lightweight processes controlled by the .Net runtime. Application Domains are
usually created by hosts like Windows Shell, ASP.NET and IE. When you run a
.NET application from the command-line, the host is the Shell. The Shell
creates a new Application Domain for every application.
46. Do I have any control over the garbage collection
algorithm?
Answer: Yes, we have a limited control over the GC
algorithm, For example, the System.GC class exposes a Collect method – this
forces the garbage collector to collect all unreferenced objects immediately.
47. What is a life span of a static variable?
Answer: A static variable’s life span is till the class is
in memory.
48. What is a Page Life Cycle of an ASP.Net page?
Answer: There are various stages described as under.
1.
Init
2.
LoadViewState
3.
LoadPostBackData
4.
Load
5.
RaisePostBackDataChangedEvent
6.
RaisePostBackEvents
7.
Pre-Render
8.
SaveViewState
9.
Render
10.
Unload
49. Can the action attribute of a server-side
<form>tag be set to a value and if not how can you possibly pass data
from a form to a subsequent Page?
Answer: No, Assigning value will not work because will be
overwritten at the time of rendering. We can assign value to it by register a
startup script which will set the action value of form on client-side. On other
hand we can use Server.Transfer or Response. Redirect.
50. How do you turn off cookies in one page of your asp.net
application?
Answer: We may not use them at the max, However to allow the
cookies or not, is client side functionality.
51. Which method do you use to redirect to user to another
page without performing a round trip to Client?
Answer: Server. Transfer (“AnotherPage.aspx”).
53. Should Validation occur on Client/Server Side for Date
Input?
Answer: Both. Client-side reduces extra round-trip.
Server-Side ensures prevention against hacking and failure against automated
requests.
54. What are the web form events?
Answer:
1.
The first event that occurs in the life of a Web
Form is the Init event. This is raised so that we can have initialization code
for the page. The controls on the page are not yet created at this point. This
event is raised once for each user of the page.
2.
The Load event follows the Init event.
Subsequently, it is raised each time the page is requested. When this event is
raised, all child controls of the Web Form are loaded and accessible. You
should be able to retrieve data and populate the controls so that they can
render themselves on the page when sent back to the client.
3.
The PreRender event happens just before the page
is rendered and sent back to the client. We don’t often handle this event;
however, it depends on the situation.
4.
The last event in the life of a Web Form is the
Unload event. This happens when the page is unloaded from memory. Final cleanup
should be done here.
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