Net Interview questions

.Net Framework Questions :
1. What is .NET Framework?
.NET Framework is a complete environment that allows devel
opers to develop, run, and deploy the following applications:
 Console applications
 Windows Forms applications
 Windows Presentation Foundation (WPF) applications
 Web applications (ASP.NET applications)
 Web services
 Windows services
 Service-oriented applications using Windows Communication Foundation (WCF)
 Workflow-enabled applications using Windows Workflow Foundation (WF)
.NET Framework also enables a developer to create sharable components to be used in distributed
computing architecture. NET Framework supports the object-oriented programming model for multiple
languages, such as Visual Basic, Visual C#, and Visual C++. .NET Framework supports multiple
programming languages in a manner that allows language interoperability. This implies that each
language can use the code written in some other language.
2. What are the main components of .NET Framework?
.NET Framework provides enormous advantages to software developers in comparison to the
advantages provided by other platforms. Microsoft has united various modern as well as existing
technologies of software development in .NET Framework. These technologies are used by developers
to develop highly efficient applications for modern as well as future business needs. The following are
the key components of .NET Framework:
 .NET Framework Class Library
 Common Language Runtime
 Dynamic Language Runtimes (DLR)
 Application Domains
 Runtime Host
 Common Type System
 Metadata and Self-Describing Components
 Cross-Language Interoperability
 .NET Framework Security
 Profiling
 Side-by-Side Execution
3. List the new features added in .NET Framework 4.0.

The following are the new features of .NET Framework 4.0:
 Improved Application Compatibility and Deployment Support
 Dynamic Language Runtime
 Managed Extensibility Framework
 Parallel Programming framework
 Improved Security Model
 Networking Improvements
 Improved Core ASP.NET Services
 Improvements in WPF 4
 Improved Entity Framework (EF)
 Integration between WCF and WF
4. What is an IL?
Intermediate Language is also known as MSIL (Microsoft Intermediate Language) or CIL (Common
Intermediate Language). All .NET source code is compiled to IL. IL is then converted to machine code
at the point where the software is installed, or at run-time by a Just-In-Time (JIT) compiler.
5. What is Manifest?
Assembly metadata is stored in Manifest. Manifest contains all the metadata needed to do the
following things
 Version of assembly.
 Security identity.
 Scope of the assembly.
 Resolve references to resources and classes.
The assembly manifest can be stored in a PE file either (an .exe or) .dll with Microsoft
intermediate language (MSIL code with Microsoft intermediate language (MSIL) code or in a
stand-alone PE file, that contains only assembly manifest information.
6. What are code contracts?
Code contracts help you to express the code assumptions and statements stating the behavior of your
code in a language-neutral way. The contracts are included in the form of pre-conditions, post-
conditions and object-invariants. The contracts help you to improve-testing by enabling run-time
checking, static contract verification, and documentation generation.
The System.Diagnostics.Contracts namespace contains static classes that are used to express
contracts in your code.
7. Name the classes that are introduced in the System.Numerics namespace.
The following two new classes are introduced in the System.Numerics namespace:

 BigInteger - Refers to a non-primitive integral type, which is used to hold a value of any
size. It has no lower and upper limit, making it possible for you to perform arithmetic
calculations with very large numbers, even with the numbers which cannot hold by double or
long.
 Complex - Represents complex numbers and enables different arithmetic operations with
complex numbers. A number represented in the form a + bi, where a is the real part,
and b is the imaginary part, is a complex number.
8. What is managed extensibility framework?
Managed extensibility framework (MEF) is a new library that is introduced as a part of .NET 4.0 and
Silverlight 4. It helps in extending your application by providing greater reuse of applications and
components. MEF provides a way for host application to consume external extensions without any
configuration requirement.
9. Explain memory-mapped files.
Memory-mapped files (MMFs) allow you map the content of a file to the logical address of an
application. These files enable the multiple processes running on the same machine to share data with
each Other. TheMemoryMappedFile.CreateFromFile() method is used to obtain
a MemoryMappedFile object that represents a persisted memory-mapped file from a file on disk.
These files are included in the System.IO.MemoryMappedFiles namespace. This namespace
contains four classes and three enumerations to help you access and secure your file mappings.
10. What is Common Type System (CTS)?
CTS is the component of CLR through which .NET Framework provides support for multiple languages
because it contains a type system that is common across all the languages. Two CTS-compliant
languages do not require type conversion when calling the code written in one language from within
the code written in another language. CTS provide a base set of data types for all the languages
supported by.NET Framework. This means that the size of integer and long variables is same across all
.NET-compliant programming languages. However, each language uses aliases for the base data types
provided by CTS. For example, CTS uses the data type system. int32 to represent a 4 byte integer
value; however, Visual Basic uses the alias integer for the same; whereas, C# uses the alias int. This
is done for the sake of clarity and simplicity.
11. Give a brief introduction on side-by-side execution. Can two applications, one using
private assembly and the other using the shared assembly be stated as side-by-side
executables?
Side-by-side execution enables you to run multiple versions of an application or component and CLR
on the same computer at the same time. As versioning is applicable only to shared assemblies and not
to private assemblies, two applications, one using a private assembly and other using a shared
assembly, cannot be stated as side-by-side executables.
12. Which method do you use to enforce garbage collection in .NET?
The System.GC.Collect() method.

13. State the differences between the Dispose() and Finalize().
CLR uses the Dispose and Finalize methods to perform garbage collection of run-time objects of .NET
applications.
The Finalize method is called automatically by the runtime. CLR has a garbage collector (GC),
which periodically checks for objects in heap that are no longer referenced by any object or program.
It calls the Finalize method to free the memory used by such objects. The Dispose method is called
by the programmer.Dispose is another method to release the memory used by an object. The
Dispose method needs to be explicitly called in code to dereference an object from the heap.
The Dispose method can be invoked only by the classes that implement the IDisposable interface.
14. What is code access security (CAS)?
Code access security (CAS) is part of the .NET security model that prevents unauthorized access of
resources and operations, and restricts the code to perform particular tasks.
15. Differentiate between managed and unmanaged code?
Managed code is the code that is executed directly by the CLR instead of the operating system. The
code compiler first compiles the managed code to intermediate language (IL) code, also called as MSIL
code. This code doesn't depend on machine configurations and can be executed on different machines.
Unmanaged code is the code that is executed directly by the operating system outside the CLR
environment. It is directly compiled to native machine code which depends on the machine
configuration.
In the managed code, since the execution of the code is governed by CLR, the runtime provides
different services, such as garbage collection, type checking, exception handling, and security support.
These services help provide uniformity in platform and language-independent behavior of managed
code applications. In the unmanaged code, the allocation of memory, type safety, and security is
required to be taken care of by the developer. If the unmanaged code is not properly handled, it may
result in memory leak. Examples of unmanaged code are ActiveX components and Win32 APIs that
execute beyond the scope of native CLR.
16. What are tuples?
Tuple is a fixed-size collection that can have elements of either same or different data types. Similar
to arrays, a user must have to specify the size of a tuple at the time of declaration. Tuples are allowed
to hold up from 1 to 8 elements and if there are more than 8 elements, then the 8th element can be
defined as another tuple. Tuples can be specified as parameter or return type of a method.
17. How can you turn-on and turn-off CAS?
YOU can use the Code Access Security Tool (Caspol.exe) to turn security on and off.
To turn off security, type the following command at the command prompt:
caspol -security off
To turn on security, type the following command at the command prompt:

caspol -security on
In the .NET Framework 4.0, for using Caspol.exe, you first need to set
the <LegacyCasPolicy> element totrue.
18. What is garbage collection? Explain the difference between garbage collections in .NET
4.0 and earlier versions.
Garbage collection prevents memory leaks during execution of programs. Garbage collector is a low-
priority process that manages the allocation and deallocation of memory for your application. It checks
for the unreferenced variables and objects. If GC finds any object that is no longer used by the
application, it frees up the memory from that object.
GC has changed a bit with the introduction of .NET 4.0. In .NET 4.0, the GC.Collect() method
contains the following overloaded methods:
GC.Collect(int)
GC.Collect(int, GCCollectionMode)
Another new feature introduced in .NET is to notify you when the GC.Collect() method is invoked
and completed successfully by using different methods. The .NET 4.0 supports a new background
garbage collection that replaces the concurrent garbage collection used in earlier versions. This
concurrent GC allocates memory while running and uses current segment (which is 16 MB on a
workstation) for that. After that, all threads are suspended. In case of background GC, a separate
ephemeral GC - gen0 and gen1 can be started, while the full GC - gen0, 1, and 2 - is already running.
19. How does CAS works?
There are two key concepts of CAS security policy- code groups and permissions. A code group
contains assemblies in it in a manner that each .NET assembly is related to a particular code group
and some permissions are granted to each code group. For example, using the default security policy,
a control downloaded from a Web site belongs to the Zone, Internet code group, which adheres to the
permissions defined by the named permission set. (Normally, the named permission set represents a
very restrictive range of permissions.)
Assembly execution involves the following steps:
1. Evidences are gathered about assembly.
2. Depending on the gathered evidences, the assembly is assigned to a code group.
3. Security rights are allocated to the assembly, depending on the code group.
4. Assembly runs as per the rights assigned to it.
20. What is Difference between NameSpace and Assembly?
Following are the differences between namespace and assembly:
 Assembly is physical grouping of logical units, Namespace, logically groups classes.

 Namespace can span multiple assembly.
21. Mention the execution process for managed code.
A piece of managed code is executed as follows:
 Choosing a language compiler
 Compiling the code to MSIL
 Compiling MSIL to native code
 Executing the code.
22. Is there a way to suppress the finalize process inside the garbage collector forcibly in
.NET?
Use the GC.SuppressFinalize() method to suppress the finalize process inside the garbage
collector forcibly in .NET.
23. How can you instantiate a tuple?
The following are two ways to instantiate a tuple:
 Using the new operator. For example,
Tuple<String, int> t = new Tuple<String, int> ("Hellow", 2);
 Using the Create factory method available in the Tuple class. For example,
Tuple<int, int, int> t = Tuple.Create<int, int, int> (2, 4, 5);
24. Which is the root namespace for fundamental types in .NET Framework?
System.Object is the root namespace for fundamental types in .NET Framework.
25. What are the improvements made in CAS in .NET 4.0?
The CAS mechanism in .NET is used to control and configure the ability of managed code. Earlier, as
this policy was applicable for only native applications, the security guarantee was limited. Therefore,
developers used to look for alternating solutions, such as operating system-level solutions. This
problem was solved in .NET Framework 4 by turning off the machine-wide security. The shared and
hosted Web applications can now run more securely. The security policy in .NET Framework 4 has
been simplified using the transparency model. This model allows you to run the Web applications
without concerning about the CAS policies.
As a result of security policy changes in .NET Framework 4.0, you may encounter compilation

warnings and runtime exceptions, if your try to use the obsolete CAS policy types and members either
implicitly or explicitly. However, you can avoid the warnings and errors by using
the <NetFx40_LegacySecurityPolicy>configuration element in the runtime settings schema to
opt into the obsolete CAS policy behavior.
26. What is Microsoft Intermediate Language (MSIL)?
The .NET Framework is shipped with compilers of all .NET programming languages to develop
programs. There are separate compilers for the Visual Basic, C#, and Visual C++ programming
languages in .NET Framework. Each .NET compiler produces an intermediate code after compiling the
source code. The intermediate code is common for all languages and is understandable only to .NET
environment. This intermediate code is known as MSIL.
27. What is lazy initialization?
Lazy initialization is a process by which an object is not initialized until it is first called in your code.
The .NET 4.0 introduces a new wrapper class, System.Lazy<T>, for executing the lazy initialization
in your application. Lazy initialization helps you to reduce the wastage of resources and memory
requirements to improve performance. It also supports thread-safety.
28. How many types of generations are there in a garbage collector?
Memory management in the CLR is divided into three generations that are build up by grouping
memory segments. Generations enhance the garbage collection performance. The following are the
three types of generations found in a garbage collector:
 Generation 0 - When an object is initialized, it is said to be in generation 0.
 Generation 1 - The objects that are under garbage collection process are considered to be in
generation 1.
 Generation 2 - Whenever new objects are created and added to the memory, they are added
to generation 0 and the old objects in generation 1 are considered to be in generation 2.
29. Explain covariance and contra-variance in .NET Framework 4.0. Give an example for
each.
In .NET 4.0, the CLR supports covariance and contravariance of types in generic interfaces and
delegates. Covariance enables you to cast a generic type to its base types, that is, you can assign a
instance of typeIEnumerable<Tl> to a variable of type IEnumerable<T2> where, T1 derives
from T2. For example,
IEnumerable<string> str1= new List<string> ();
IEnumerable<object> str2= str1;
Contravariance allows you to assign a variable of Action<base> to a variable of
type Action<derived>. For example,
IComparer<object> obj1 = GetComparer()
IComparer<string> obj2 = obj1;

.NET framework 4.0 uses some language keywords (out and in) to annotate covariance and contra-
variance. Out is used for covariance, while in is used for contra-variance.
Variance can be applied only to reference types, generic interfaces, and generic delegates. These
cannot be applied to value types and generic types.
30. How do you instantiate a complex number?
The following are the different ways to assign a value to a complex number:
By passing two Double values to its constructor. The first value represents the real, and the second
value represents imaginary part of a complex number.
For example,
Complex c1 = new Complex(5, 8); /* It represents (5, 8) */
By assigning a Byte, SByte, Intl6, UIntl6, Int32, UInt32, Int64, UInt64, Single,
or Double value to aComplex object. The assigned value represents the real part of the complex
number, and its imaginary part becomes 0. For example,
Complex c2 = 15.3; /* It represents (15.3, 0) */
By casting a Decimal or BigInteger value to a Complex object.
For example,
Complex c3 = (Complex) 14.7; /* It represents (14.7, 0) */
Assigning the value returned by an operator to a Complex variable.
For example,
Complex c4 = c1 + c2; /* It represents (20.3, 8) */
31. What is Common Language Specification (CLS)?
CLS is a set of basic rules, which must be followed by each .NET language to be a .NET- compliant
language. It enables interoperability between two .NET-compliant languages. CLS is a subset of CTS;
therefore, the languages supported by CLS can use each other's class libraries similar to their own.
Application programming interfaces (APIs), which are designed by following the rules defined in CLS
can be used by all .NET-compliant languages.
32. What is the role of the JIT compiler in .NET Framework?

The JIT compiler is an important element of CLR, which loads MSIL on target machines for execution.
The MSIL is stored in .NET assemblies after the developer has compiled the code written in any .NET-
compliant programming language, such as Visual Basic and C#.
JIT compiler translates the MSIL code of an assembly and uses the CPU architecture of the target
machine to execute a .NET application. It also stores the resulting native code so that it is accessible
for subsequent calls. If a code executing on a target machine calls a non-native method, the JIT
compiler converts the MSIL of that method into native code. JIT compiler also enforces type-safety in
runtime environment of .NET Framework. It checks for the values that are passed to parameters of
any method.
For example, the JIT compiler detects any event, if a user tries to assign a 32-bit value to a parameter
that can only accept 8-bit value.
33. What is difference between System.String and System.StringBuilder classes?
String and StringBuilder classes are used to store string values but the difference in them is that
String is immutable (read only) by nature, because a value once assigned to a String object cannot be
changed after its creation. When the value in the String object is modified, a new object is created, in
memory, with a new value assigned to the String object. On the other hand,
the StringBuilder class is mutable, as it occupies the same space even if you change the value.
The StringBuilder class is more efficient where you have to perform a large amount of string
manipulation.
34. Describe the roles of CLR in .NET Framework.
CLR provides an environment to execute .NET applications on target machines. CLR is also a common
runtime environment for all .NET code irrespective of their programming language, as the compilers of
respective language in .NET Framework convert every source code into a common language known as
MSIL or IL (Intermediate Language).
CLR also provides various services to execute processes, such as memory management service and
security services. CLR performs various tasks to manage the execution process of .NET applications.
The responsibilities of CLR are listed as follows:
 Automatic memory management
 Garbage Collection
 Code Access Security
 Code verification
 JIT compilation of .NET code
35. What is the difference between int and int32.
There is no difference between int and int32. System.Int32 is a .NET Class and int is an alias
name forSystem.Int32.

Object-Oriented Programming :
1. What is object-oriented programming (OOP)?
OOP is a technique to develop logical modules, such as classes that contain properties, methods,
fields, and events. An object is created in the program to represent a class. Therefore, an object
encapsulates all the features, such as data and behavior that are associated to a class. OOP allows
developers to develop modular programs and assemble them as software. Objects are used to access
data and behaviors of different software modules, such as classes, namespaces, and sharable
assemblies. .NET Framework supports only OOP languages, such as Visual Basic .NET, Visual C#, and
Visual C++.
2. What is a class?
A class describes all the attributes of objects, as well as the methods that implement the behavior of
member objects. It is a comprehensive data type, which represents a blue print of objects. It is a
template of object.
A class can be defined as the primary building block of OOP. It also serves as a template that
describes the properties, state, and behaviors common to a particular group of obje cts.
A class contains data and behavior of an entity. For example, the aircraft class can contain data, such
as model number, category, and color and behavior, such as duration of flight, speed, and number of
passengers. A class inherits the data members and behaviors of other classes by extending from
them.
3. What is an object?
They are instance of classes. It is a basic unit of a system. An object is an entity that has attributes,
behavior, and identity. Attributes and behavior of an object are defined by the class definition.
4. What is the relationship between a class and an object?
A class acts as a blue-print that defines the properties, states, and behaviors that are common to a
number of objects. An object is an instance of the cass. For example, you have a class
called Vehicle and Car is the object of that class. You can create any number of objects for the class
named Vehicle, such as Van, Truck, and Auto.
The new operator is used to create an object of a class. When an object of a class is instantiated, the
system allocates memory for every data member that is present in the class.
5. Explain the basic features of OOPs.
The following are the four basic features of OOP:

 Abstraction - Refers to the process of exposing only the relevant and essential data to the
users without showing unnecessary information.
 Polymorphism - Allows you to use an entity in multiple forms.
 Encapsulation - Prevents the data from unwanted access by binding of code and data in a
single unit called object.
 Inheritance - Promotes the reusability of code and eliminates the use of redundant code. It is
the property through which a child class obtains all the features defined in its parent class.
When a class inherits the common properties of another class, the class inheriting the
properties is called a derived class and the class that allows inheritance of its common
properties is called a base class.
6. What is the difference between arrays and collection?
Array:
1. You need to specify the size of an array at the time of its declaration. It cannot be resized
dynamically.
2. The members of an array should be of the same data type.
Collection:
1. The size of a collection can be adjusted dynamically, as per the user's requirement. It does not
have fixed size.
2. Collection can have elements of different types.
7. What are collections and generics?
A collection can be defined as a group of related items that can be referred to as a single unit.
TheSystem.Collections namespace provides you with many classes and interfaces. Some of them
are -ArrayList, List, Stack, ICollection, IEnumerable, and IDictionary. Generics provide
the type-safety to your class at the compile time. While creating a data structure, you never need to
specify the data type at the time of declaration. The System.Collections.Generic namespace
contains all the generic collections.
8. How can you prevent your class to be inherited further?
You can prevent a class from being inherited further by defining it with the sealed keyword.
9. What is the index value of the first element in an array?
In an array, the index value of the first element is 0 (zero).
10. Can you specify the accessibility modifier for methods inside the interface?
All the methods inside an interface are always public, by default. You cannot specify any other
access modifier for them.

11. Is it possible for a class to inherit the constructor of its base class?
No, a class cannot inherit the constructor of its base class.
12. How is method overriding different from method overloading?
Overriding involves the creation of two or more methods with the same name and same signature in
different classes (one of them should be parent class and other should be child).
Overloading is a concept of using a method at different places with same name and different
signatures within the same class.
13. What is the difference between a class and a structure?
Class:
1. A class is a reference type.
2. While instantiating a class, CLR allocates memory for its instance in heap.
3. Classes support inheritance.
4. Variables of a class can be assigned as null.
5. Class can contain constructor/destructor.
Structure:
1. A structure is a value type.
2. In structure, memory is allocated on stack.
3. Structures do not support inheritance.
4. Structure members cannot have null values.
5. Structure does not require constructor/destructor and members can be initialiazed
automatically.
14. What are similarities between a class and a structure.
Structures and classes are the two most important data structures that are used by programmers to
build modular programs by using OOP languages, such as Visual Basic .NET, and Visual C#. The
following are some of the similarities between a class and a structure:
 Access specifiers, such as public, private, and protected, are identically used in
structures and classes to restrict the access of their data and methods outside their body.
 The access level for class members and struct members, including nested classes and structs,
is private by default. Private nested types are not accessible from outside the containing type.
 Both can have constructors, methods, properties, fields, constants, enumerations, events, and
event handlers.
 Both structures and classes can implement interfaces to use multiple-inheritance in code.
 Both structures and classes can have constructors with parameter.
 Both structures and classes can have delegates and events.

15. What is a multicast delegate?
Each delegate object holds reference to a single method. However, it is possible for a delegate object
to hold references of and invoke multiple methods. Such delegate objects are called multicast
delegates or combinable delegates.
16. Can you declare an overridden method to be static if the original method is not static?
No. Two virtual methods must have the same signature.
17. Why is the virtual keyword used in code?
The virtual keyword is used while defining a class to specify that the methods and the properties of
that class can be overridden in derived classes.
18. Can you allow a class to be inherited, but prevent a method from being overridden in
C#?
Yes. Just declare the class public and make the method sealed.
19. Define enumeration?
Enumeration is defined as a value type that consists of a set of named values. These values are
constants and are called enumerators. An enumeration type is declared using the enum keyword. Each
enumerator in an enumeration is associated with an underlying type that is set, by default, on the
enumerator. The following is an example that creates an enumeration to store different varieties of
fruits:
enum Fruits {Mango, Apple, orange, Guava};
In the preceding example, an enumeration Fruits is created, where number 0 is associated
with Mango, number 1 with Apple, number 2 with Orange, and number 3 with Guava. You can
access the enumerators of an enumeration by these values.
20. In which namespace, all .NET collection classes are contained?
The System.Collections namespace contains all the collection classes.
21. Is it a good practice to handle exceptions in code?
Yes, you must handle exceptions in code so that you can deal with any unexpected situations that
occur when a program is running. For example, dividing a number by zero or passing a string value to
a variable that holds an integer value would result in an exception.
22. Explain the concept of constructor?

Constructor is a special method of a class, which is called automatically when the instance of a class is
created. It is created with the same name as the class and initializes all class members, whenever you
access the class. The main features of a constructor are as follows:
 Constructors do not have any return type
 Constructors are always public
 It is not mandatory to declare a constructor; it is invoked automatically by .NET Framework.
23. Can you inherit private members of a class?
No, you cannot inherit private members of a class because private members are accessible only
to that class and not outside that class.
24. Does .NET support multiple inheritance?
.NET does not support multiple inheritance directly because in .NET, a class cannot inherit from more
than one class. .NET supports multiple inheritance through interfaces.
25. How has exception handling changed in .NET Framework 4.0?
In .NET 4.0, a new namespace, System.Runtime.ExceptionServices, has been introduced which
contains the following classes for handling exceptions in a better and advanced manner:
 HandleProcessCorruptedStateExceptionsAttribute Class - Enables managed code to
handle the corrupted state exceptions that occur in an operating system. These exceptions
cannot be caught by specifying the try...catch block. To handle such exceptions, you can
apply this attribute to the method that is assigned to handle these exceptions.
 FirstChanceExceptionEventArgs Class - Generates an event whenever a managed
exception first occurs in your code, before the common language runtime begins searching for
event handlers.
26. What is a delegate?
A delegate is similar to a class that is used for storing the reference to a method and invoking that
method at runtime, as required. A delegate can hold the reference of only those methods whose
signatures are same as that of the delegate. Some of the examples of delegates are type -safe
functions, pointers, or callbacks.
27. What is the syntax to inherit from a class in C#?
When a class is derived from another class, then the members of the base class become the members
of the derived class. The access modifier used while accessing members of the base class specifies the
access status of the base class members inside the derived class.
The syntax to inherit a class from another class in C# is as follows:
class MyNewClass : MyBaseclass

28. State the features of an interface.
An interface is a template that contains only the signature of methods. The signature of a method
consists of the numbers of parameters, the type of parameter (value, reference, or output), and the
order of parameters. An interface has no implementation on its own because it contains only the
definition of methods without any method body. An interface is defined using
the interface keyword. Moreover, you cannot instantiate an interface. The various features of an
interface are as follows:
 An interface is used to implement multiple inheritance in code. This feature of an interface is
quite different from that of abstract classes because a class cannot derive the features of more
than one class but can easily implement multiple interfaces.
 It defines a specific set of methods and their arguments.
 Variables in interface must be declared as public, static, and final while methods must
be publicand abstract.
 A class implementing an interface must implement all of its methods.
 An interface can derive from more than one interface.
29. Can you use the 'throws' clause to raise an exception?
No, the throws clause cannot be used to raise an exception. The throw statement signals the
occurrence of an exception during the execution of a program. When the program encounters
a throw statement, the method terminates and returns the error to the calling method.
30. Define an array.
An array is defined as a homogeneous collection of elements, stored at contiguous memory locations,
which can be referred by the same variable name. All the elements of an array variable can be
accessed by index values. An Index value specifies the position of a particular element in an array
variable.
31. What are methods?
Methods are the building blocks of a class, in which they are linked together to share and process data
to produce the result. In other words, a method is a block of code that contains a series of statements
and represents the behavior of a class. While declaring a method you need to specify the access
specifier, the return value, the name of the method, and the method parameters. All these combined
together is called the signature of the method.
32. What is a namespace?
Namespace is considered as a container that contains functionally related group of classes and other
types.
33. Do events have return type?
No, events do not have return type.
34. What is the function of the Try-Catch-Finally block?

The try block encloses those statements that can cause exception and the catch block handles the
exception, if it occurs. Catch block contains the statements that have to be executed, when an
exception occurs. Thefinally block always executes, irrespective of the fact whether or not an
exception has occurred. The finallyblock is generally used to perform the cleanup process. If any
exception occurs in the try block, the program control directly transfers to its
corresponding catch block and later to the finally block. If no exception occurs inside
the try block, then the program control transfers directly to the finally block.
35. How can you prevent a class from overriding in C# and Visual Basic?
You can prevent a class from overriding in C# by using the sealed keyword; whereas,
the NotInheritablekeyword is used to prevent a class from overriding in Visual Basic.
36. What are abstract classes? What are the distinct characteristics of an abstract class?
An abstract class is a class that cannot be instantiated and is always used as a base class.
The following are the characteristics of an abstract class:
 You cannot instantiate an abstract class directly. This implies that you cannot create an object
of the abstract class; it must be inherited.
 You can have abstract as well as non-abstract members in an abstract class.
 You must declare at least one abstract method in the abstract class.
 An abstract class is always public.
 An abstract class is declared using the abstract keyword.
The basic purpose of an abstract class is to provide a common definition of the base cla ss that multiple
derived classes can share.
37. Give a brief description of properties in C# and the advantages that are obtained by
using them in programs.
In C#, a property is a way to expose an internal data element of a class in a simple and intuitive
manner. In other words, it is a simple extension of data fields. You can create a property by defining
an externally available name and then writing the set and get property accessors. The get property
accessor is used to return the property value. The set property accessor is used to assign a new value
to the property.
38. Explain different types of inheritance.
Inheritance in OOP is of four types:
 Single inheritance - Contains one base class and one derived class
 Hierarchical inheritance - Contains one base class and multiple derived classes of the same
base class
 Multilevel inheritance - Contains a class derived from a derived class
 Multiple inheritance - Contains several base classes and a derived class

All .NET languages supports single, hierarchical, and multilevel inheritance. They do not support
multiple inheritance because in these languages, a derived class cannot have more than one base
class. However, you can implement multiple inheritance in.NET through interfaces.
39. You have defined a destructor in a class that you have developed by using the C#
programming language, but the destructor never executed. Why did the destructor not
execute?
The runtime environment automatically invokes the destructor of a class to release the resources that
are occupied by variables and methods of an object. However, in C#, programmers cannot control the
timing for invoking destructors, as Garbage Collector is only responsible for releasing the resources
used by an object. Garbage Collector automatically gets information about unreferenced objects from
.NET's runtime environment and then invokes the Finalize() method.
Although, it is not preferable to force Garbage Collector to perform garbage collection and retrieve all
inaccessible memory, programmers can use the Collect() method of the Garbage Collector class to
forcefully execute Garbage Collector.
40. What is a hashtable?
Hashtable is a data structure that implements the IDictionary interface. It is used to store
multiple items and each of these items is associated with a unique string key. Each item can be
accessed using the key associated with it. In short, hashtable is an object holding the key-value pairs.
41. Can users define their own exceptions in code?
Yes, customized exceptions can be defined in code by deriving from the System.Exception class.
42. Is it possible to execute two catch blocks?
You are allowed to include more than one catch block in your program; however, it is not possible to
execute them in one go. Whenever, an exception occurs in your program, the correct catch block is
executed and the control goes to the finally block.
43. What do you mean by data encapsulation?
Data encapsulation is a concept of binding data and code in single unit called object and hiding all the
implementation details of a class from the user. It prevents unauthorized access of data and restricts
the user to use the necessary data only.
44. What is the difference between procedural and object-oriented programming?
Procedural programming is based upon the modular approach in which the larger programs are broken
into procedures. Each procedure is a set of instructions that are executed one after another. On the
other hand, OOP is based upon objects. An object consists of various elements, such as methods and
variables.

Access modifiers are not used in procedural programming, which implies that the entire data can be
accessed freely anywhere in the program. In OOP, you can specify the scope of a particular data by
using access modifiers - public, private, internal, protected, and protected internal.
45. Explain the concept of destructor?
A destructor is a special method for a class and is invoked automatically when an object is finally
destroyed. The name of the destructor is also same as that of the class but is followed by a prefix tilde
(~).
A destructor is used to free the dynamic allocated memory and release the resources. You can,
however, implement a custom method that allows you to control object destruction by calling the
destructor.
The main features of a destructor are as follows:
 Destructors do not have any return type
 Similar to constructors, destructors are also always public
 Destructors cannot be overloaded.
46. Can you declare a private class in a namespace?
The classes in a namespace are internal, by default. However, you can explicitly declare them
as public only and not as private, protected, or protected internal. The nested classes can
be declared as private,protected, or protected internal.
47. A structure in C# can implement one or more interfaces. Is it true or false?
Yes, it is true. Like classes, in C#, structures can implement one or more interfaces.
48. What is a static constructor?
Static constructors are introduced with C# to initialize the static data of a class. CLR calls the static
constructor before the first instance is created.
The static constructor has the following features:
 No access specifier is required to define it.
 You cannot pass parameters in static constructor.
 A class can have only one static constructor.
 It can access only static members of the class.
 It is invoked only once, when the program execution begins.
49. What are the different ways a method can be overloaded?
The different ways to overload a method are given as follows:

 By changing the number of parameters used
 By changing the order of parameters
 By using different data types for the parameters
50. Differentiate between an abstract class and an interface.
Abstract Class:
1. A class can extend only one abstract class
2. The members of abstract class can be private as well as protected.
3. Abstract classes should have subclasses
4. Any class can extend an abstract class.
5. Methods in abstract class can be abstract as well as concrete.
6. There can be a constructor for abstract class.
7. The class extending the abstract class may or may not implement any of its method.
8. An abstract class can implement methods.
Interface
1. A class can implement several interfaces
2. An interface can only have public members.
3. Interfaces must have implementations by classes
4. Only an interface can extend another interface.
5. All methods in an interface should be abstract
6. Interface does not have constructor.
7. All methods of interface need to be implemented by a class implementing that interface.
8. Interfaces cannot contain body of any of its method.
51. What are queues and stacks?
Stacks refer to a list in which all items are accessed and processed on the Last-In-First-Out (LIFO)
basis. In a stack, elements are inserted (push operation) and deleted (pop operation) from the same
end called top.
Queues refer to a list in which insertion and deletion of an item is done on the First-In-First-Out (FIFO)
basis. The items in a queue are inserted from the one end, called the rear end, and are deleted from
the other end, called the front end of the queue.
52. Define an event.
Whenever an action takes place in a class, that class provides a notification to other classes or objects
that are assigned to perform particular tasks. These notifications are called events. For example, when
a button is clicked, the class generates an event called Click. An event can be declared with the help
of the event keyword.
53. What are structures?

Structure is a heterogeneous collection of elements referenced by the same name. A structure is
declared using the struct keyword. The following is an example that creates a structure to store an
employee's information:
struct emp
{
fixed int empID[15];
fixed char name[30];
fixed char addr[50];
fixed char dept[15];
fixed char desig[15];
}
The preceding example defines a structure emp and the members of this structure specify the
information of an employee.
54. When do you really need to create an abstract class?
We define abstract classes when we define a template that needs to be followed by all the derived
classes.

ASP .Net Questions :
1. What is ASP?
Active Server Pages (ASP), also known as Classic ASP, is a Microsoft's server-side technology, which
helps in creating dynamic and user-friendly Web pages. It uses different scripting languages to create
dynamic Web pages, which can be run on any type of browser. The Web pages are built by using
either VBScript or JavaScript and these Web pages have access to the same services as Windows
application, including ADO (ActiveX Data Objects) for database access, SMTP (Simple Mail Transfer
Protocol) for e-mail, and the entire COM (Component Object Model) structure used in the Windows
environment. ASP is implemented through a dynamic-link library (asp.dll) that is called by the IIS
server when a Web page is requested from the server.
2. What is ASP.NET?
ASP.NET is a specification developed by Microsoft to create dynamic Web applications, Web sites, and
Web services. It is a part of .NET Framework. You can create ASP.NET applications in most of the .NET
compatible languages, such as Visual Basic, C#, and J#. The ASP.NET compiles the Web pages and
provides much better performance than scripting languages, such as VBScript. The Web Forms
support to create powerful forms-based Web pages. You can use ASP.NET Web server controls to
create interactive Web applications. With the help of Web server controls, you can easily create a Web
application.
3. What is the basic difference between ASP and ASP.NET?
The basic difference between ASP and ASP.NET is that ASP is interpreted; whereas, ASP.NET is
compiled. This implies that since ASP uses VBScript; therefore, when an ASP page is executed, it is
interpreted. On the other hand, ASP.NET uses .NET languages, such as C# and VB.NET, which are
compiled to Microsoft Intermediate Language (MSIL).
4. In which event are the controls fully loaded?
Page load event guarantees that all controls are fully loaded. Controls are also accessed
in Page_Init events but you will see that view state is not fully loaded during this event
5. How can we identify that the Page is Post Back?
Page object has an "IsPostBack" property, which can be checked to know that is the page posted
back.
6. What is the lifespan for items stored in ViewState?
The items stored in ViewState live until the lifetime of the current page expires including the
postbacks to the same page.

7. How information about the user's locale can be accessed?
The information regarding a user's locale can be accessed by using
the System.Web.UI.Page.Cultureproperty.
8. What is the difference between SQL notification and SQL invalidation?
The SQL cache notification generates notifications when the data of a database changes, on which
your cache item depends. The SQL cache invalidation makes a cached item invalid when the data
stored in a SQL server database changes.
9. Which is the parent class of the Web server control?
The System.Web.Ul.Control class is the parent class for all Web server controls.
10. Can you set which type of comparison you want to perform by
the CompareValidator control?
Yes, by setting the Operator property of the CompareValidator control.
11. What is the behavior of a Web browser when it receives an invalid element?
The behavior of a Web browser when it receives an invalid element depends on the browser that you
use to browse your application. Most of the browsers ignore the invalid element; whereas, some of
them display the invalid elements on the page.
12. What are the advantages of the code-behind feature?
The code-behind feature of ASP.NET offers a number of advantages:
 Makes code easy to understand and debug by separating application logic from HTML tags
 Provides the isolation of effort between graphic designers and software engineers
 Removes the problems of browser incompatibility by providing code files to exist on the Web
server and supporting Web pages to be compiled on demand.
13. How do you sign out from forms authentication?
The FormsAuthentication.Signout() method is used to sign out from the forms authentication.
14. What is AutoPostBack?
If you want a control to postback automatically when an event is raised, you need to set
the AutoPostBackproperty of the control to True.

15. What is the function of the ViewState property?
The ASP.NET 4.0 introduced a new property called ViewStateMode for the Control class. Now you
can enable the view state to an individual control even if the view state for an ASP.NET page is
disabled.
16. Why do you use the App_Code folder in ASP.NET?
The App_Code folder is automatically present in the project. It stores the files, such as classes, typed
data set, text files, and reports. If this folder is not available in the application, you can add this
folder. One of the important features of the App_Code folder is that only one dll is created for the
complete folder, irrespective of how many files it contains.
17. Define a multilingual Web site.
A multilingual Web site serves content in a number of languages. It contains multiple copies for its
content and other resources, such as date and time, in different languages.
18. What is an ASP.NET Web Form?
ASP.NET Web forms are designed to use controls and features that are almost as powerful as the ones
used with Windows forms, and so they are called as Web forms. The Web form uses a server-side
object model that allows you to create functional controls, which are executed on the server and are
rendered as HTML on the client. The attribute, runat="server", associated with a server control
indicates that the Web form must be processed on the server.
19. What is the difference between a default skin and a named skin?
The default skin is applied to all the Web server controls in a Web form, which are of similar type, and
it does not provide a Skin ID attribute. The named skin provides a Skin ID attribute and users have to
set the Skin ID property to apply it.
20. What is IIS? Why is it used?
Internet Information Services (IIS) is created by Microsoft to provide Internet-based services to
ASP.NET Web applications. It makes your computer to work as a Web server and provides the
functionality to develop and deploy Web applications on the server. IIS handles the request and
response cycle on the Web server. It also offers the services of SMTP and FrontPage server
extensions. The SMTP is used to send emails and use FrontPage server extensions to get the dynamic
features of IIS, such as form handler.

21. What is Query String? What are its advantages and limitations?
The Query String helps in sending the page information to the server.
The Query String has the following advantages:
 Every browser works with Query Strings.
 It does not require server resources and so does not exert any kind of burden on the server.
The following are the limitations of Query String:
 Information must be within the limit because URL does not support many characters.
 Information is clearly visible to the user, which leads to security threats.
22. What is actually returned from server to the browser when a browser requests an .aspx
file and the file is displayed?
When a browser requests an .aspx file then the server returns a response, which is rendered into a
HTML string.
23. How can you display all validation messages in one control?
The ValidationSummary control displays all validation messages in one control.
24. Which two new properties are added in ASP.NET 4.0 Page class?
The two new properties added in the Page class are MetaKeyword and MetaDescription.
25. What is tracing? Where is it used?
Tracing displays the details about how the code was executed. It refers to collecting information about
the application while it is running. Tracing information can help you to troubleshoot an application. It
enables you to record information in various log files about the errors that might occur at run time.
You can analyze these log files to find the cause of the errors.
In .NET, we have objects called Trace Listeners. A listener is an object that gets the trace output and
stores it to different places, such as a window, a file on your locale drive, or a SQL Server.
The System.Diagnostics namespace contains the predefined interfaces, classes, and structures
that are used for tracing. It supplies two classes, Trace and Debug, which allow you to write errors
and logs related to the application execution. Trace listeners are objects that collect the output of
tracing processes.

26. What is the difference between authentication and authorization?
Authentication verifies the identity of a user and authorization is a process where you can check
whether or not the identity has access rights to the system. In other words, you can say that
authentication is a procedure of getting some credentials from the users and verify the user's identity
against those credentials. Authorization is a procedure of granting access of particular resources to an
authenticated user. You should note that authentication always takes place before authorization.
27. How can you register a custom server control to a Web page?
You can register a custom server control to a Web page using the @Register directive.
28. Which ASP.NET objects encapsulate the state of the client and the browser?
The Session object encapsulates the state of the client and browser.
29. Differentiate globalization and localization.
The globalization is a technique to identify the specific part of a Web application that is different for
different languages and make separate that portion from the core of the Web application. The
localization is a procedure of configuring a Web application to be supported for a specific language or
locale.
30. What is ViewState?
The ViewState is a feature used by ASP.NET Web page to store the value of a page and its controls
just before posting the page. Once the page is posted, the first task by the page processing is to
restore the ViewState to get the values of the controls.
31. Which method is used to force all the validation controls to run?
The Page.Validate() method is used to force all the validation controls to run and to perform
validation.
32. Which method has been introduced in ASP.NET 4.0 to redirect a page permanently?
The RedirectPermanent() method added in ASP.NET 4.0 to redirect a page permanently. The
following code snippet is an example of the RedirectPermanent() method:
RedirectPermanent("/path/Aboutus.aspx");

33. How can you send an email message from an ASP.NET Web page?
You can use the System.Net.Mail.MailMessage and the System.Net.Mail.SmtpMail classes
to send an email in your Web pages. In order to send an email through your mail server, you need to
create an object of the SmtpClient class and set the server name, port, and credentials.
34. What is the difference between
the Response.Write() and Response.Output.Write() methods?
The Response.Write() method allows you to write the normal output; whereas,
theResponse.Output.Write() method allows you to write the formatted output.
35. What does the Orientation property do in a Menu control?
Orientation property of the Menu control sets the horizontal or vertical display of a menu on a Web
page. By default, the orientation is vertical.
36. Differentiate between client-side and server-side validations in Web pages.
Client-side validations take place at the client end with the help of JavaScript and VBScript before the
Web page is sent to the server. On the other hand, server-side validations take place at the server
end.
37. How does a content page differ from a master page?
A content page does not have complete HTML source code; whereas a master page has complete
HTML source code inside its source file.
7638. Suppose you want an ASP.NET function (client side) executed on the MouseOver
event of a button. Where do you add an event handler?
The event handler is added to the Add() method of the Attributes property.
39. What is the default timeout for a Cookie?
The default time duration for a Cookie is 30 minutes.
40. What are HTTP handlers in ASP.NET?
HTTP handlers, as the name suggests, are used to handle user requests for Web application resources.
They are the backbone of the request-response model of Web applications. There is a specific event
handler to handle the request for each user request type and send back the corresponding response
object.
Each user requests to the IIS Web server flows through the HTTP pipeline, which refers to a series of
components (HTTP modules and HTTP handlers) to process the request. HTTP modules act as filters to
process the request as it passes through the HTTP pipeline. The request, after passing through the

HTTP modules, is assigned to an HTTP handler that determines the response of the server to the user
request. The response then passes through the HTTP modules once again and is then sent back to the
user.
You can define HTTP handlers in the <httpHandlers> element of a configuration file.
The <add> element tag is used to add new handlers and the <remove> element tag is used to
remove existing handlers. To create an HTTP handler, you need to define a class that implements
the IHttpHandler interface.ndndr6bnd
41. What are the events that happen when a client requests an ASP.NET page from IIS
server?
The following events happen when a client requests an ASP.NET page from the IIS server:
1. User requests for an application resource.
2. The integrated request-processing pipeline receives the first user request.
3. Response objects are created for each user request.
4. An object of the HttpApplication class is created and allocated to the Request object.
5. The HttpApplication class processes the user request.
42. Explain file-based dependency and key-based dependency.
In file-based dependency, you have to depend on a file that is saved in a disk. In key-based
dependency, you have to depend on another cached item.
43. How can you implement the postback property of an ASP.NET control?
You need to set the AutoPostBack property to True to implement the PostBack property of
controls.
44. Explain how Cookies work. Give an example of Cookie abuse.
The server tells the browser to put some files in a cookie, and the client then sends all the cookies for
the domain in each request. An example of cookie abuse is large cookies affecting the network traffic.
45. Explain login controls.
Login controls are built-in controls in ASP.Net for providing a login solution to ASP.NET application.
The login controls use the membership system to authenticate a user credentials for a Web site.
There are many controls in login controls.
 ChangePassword control - Allows users to change their password.
 CreateUserWizard control - Provides an interface to the user to register for that Web site.
 Login control - Provides an interface for user authentication. It consists of a set of controls,
such asTextBox, Label, Button, CheckBox, HyperLink.
 LoginView control - Displays appropriate information to different users according to the
user's status.

 LoginStatus control - Shows a login link to users, who are not authenticated and logout link,
who are authenticated
 LoginName control - Displays a user name, if the user logs in.
 PasswordRecovery control - Allows users to get back the password through an e-mail, if
they forget.
46. What is the use of PlaceHolder control? Can we see it at runtime?
The PlaceHolder control acts as a container for those controls that are dynamically generated at
runtime. We cannot see it at runtime because it does not produce any visible output. It used only as a
container.
47. What setting must be added in the configuration file to deny a particular user from
accessing the secured resources?
To deny a particular user form accessing the secured resources, the web.config file must contain
the following code:
<authorization >
<deny users="username" />
</authorization>
48. What are the event handlers that can be included in the Global.asax file?
The Global.asax file contains some of the following important event handlers:
 Application_Error
 Application_Start
 Application_End
 Session_Start
 Session_End
49. What is the difference between page-level caching and fragment caching?
In the page-level caching, an entire Web page is cached; whereas, in the fragment caching, a part of
the Web page, such as a user control added to the Web page, is cached.
50. Make a list of all templates of the Repeater control.
The Repeater control contains the following templates:
 ItemTemplate
 AlternatingltemTemplate
 SeparatorTemplate
 HeaderTemplate
 FooterTemplate

51. Describe the complete lifecycle of a Web page.
When we execute a Web page, it passes from the following stages, which are collectively known as
Web page lifecycle:
 Page request - During this stage, ASP.NET makes sure the page either parsed or compiled
and a cached version of the page can be sent in response
 Start - During this stage sets the Request and Response page properties and the page check
the page request is either a postback or a new request
 Page Initialization - During this stage, the page initialize and the control's Unique Id
property are set
 Load - During this stage, if the request is postback, the control properties are loaded without
loading the view state and control state otherwise loads the view state
 Validation - During this stage, the controls are validated
 Postback event handling - During this stage, if the request is a postback, handles the event
 Rendering - During this stage, the page invokes the Render method to each control for return
the output
 Unload - During this stage, when the page is completely rendered and sent to the client, the
page is unloaded.
52. How can you assign page specific attributes in an ASP.NET application?
The @Page directive is responsible for this.
53. Which method is used to post a Web page to another Web page?
The Respose.Redirect method is used to post a page to another page, as shown in the following
code snippet: Response.Redirect("DestinationPageName.aspx");
54. What is a Cookie? Where is it used in ASP.NET?
Cookie is a lightweight executable program, which the server posts to client machines. Cookies store
the identity of a user at the first visit of the Web site and validate them later on the next visits for
their authenticity. The values of a cookie can be transferred between the user's request and the
server's response.
55. What are Custom User Controls in ASP.NET?
The custom user controls are the controls that are defined by developers. These controls are a mixture
of custom behavior and predefined behavior. These controls work similar to other Web server controls.
56. What does the .WebPart file do?
The .WebPart file explains the settings of a Web Parts control that can be included to a specified zone
on a Web page.

57. How can you enable impersonation in the web.config file?
To enable impersonation in the web.confing file, you need to include the <identity> element in
theweb.config file and set the impersonate attribute to true as shown in the following code snippet:
<identity impersonate = "true" />
58. How can you identify that the page is PostBack?
The Page object uses the IsPostBack property to check whether the page is posted back or not. If
the page is postback, this property is set to true.
59. In which database is the information, such as membership, role management, profile,
and Web parts personalization, stored?
The aspnetdb database stores all information.
60. What is State Management? How many ways are there to maintain a state in .NET?
State management is used to store information requests. The state management is used to trace the
information or data that affect the state of the applications.
There are two ways to maintain a state in .NET, Client-Based state management and Server-Based
state management.
The following techniques can be used to implement the Client-Based state management:
 View State
 Hidden Fields
 Cookies
 Query Strings
 Control State
The following techniques can be used to implement Server-Based state management:
 Application State
 Session State
 Profile Properties
61. What do you understand by aggregate dependency?
Aggregate dependency allows multiple dependencies to be aggregated for content that depends on
more than one resource. In such type of dependency, you need to depend on the sum of all the
defined dependencies to remove a data item from the cache.

62. How can you ensure that no one has tampered with ViewState in a Web page?
To ensure that no one has tampered with ViewState in a Web page, set
the EnableViewStateMac property to True.
63. What is the difference between adding items into cache through the Add() method and
through theInsert() method?
Both methods work in a similar way except that the Cache.Add() function returns an object that
represents the item you added in the cache. The Cache.Insert() function can replace an existing
item in the cache, which is not possible using the Cache.Add() method.
64. Explain the cookie less session and its working.
ASP.NET manages the session state in the same process that processes the request and does not
create a cookie. It is known as a cookie less session. If cookies are not available, a session is tracked
by adding a session identifier to the URL. The cookie less session is enabled using the following code
snippet:<sessionState cookieless="true" />
65. What is a round trip?
The trip of a Web page from the client to the server and then back to the client is known as a round
trip.
66. What are the major built-in objects in ASP.NET?
The major built-in objects in ASP.NET are as follows:
 Application
 Request
 Response
 Server
 Session
 Context
 Trace
67. Where should the data validations be performed-at the client side or at the server side
and why?
Data validations should be done primarily at the client side and the server-side validation should be
avoided because it makes server task overloaded. If the client-side validation is not available, you can
use server-side validation. When a user sends a request to the server, the validation controls are
invoked to check the user input one by one.
68. Why do we need nested master pages in a Web site?

When we have several hierarchical levels in a Web site, then we use nested master pages in the Web
site.
69. How can you dynamically add user controls to a page?
User controls can be dynamically loaded by adding a Web User Control page in the application and
adding the control on this page.
70. What is the appSettings Section in the web.config file?
The web.config file sets the configuration for a Web project. The appSettings block in
configuration file sets the user-defined values for the whole application.
For example, in the following code snippet, the specified ConnectionString section is used
throughout the project for database connection:
<configuration>
<appSettings>
<add key="ConnectionString" value="server=indiabixserver; pwd=dbpassword;
database=indiabix" />
</appSettings>
...
71. What type of code, client-side or server-side, is found in a code-behind file of a Web
page?
A code-behind file contains the server-side code, which means that the code contained in a code-
behind file is executed at the server.
72. To which class a Web form belongs to in the .NET Framework class hierarchy?
A Web form belongs to the System.Web.UI.Page class.
73. What does the "EnableViewState" property do? Why do we want it On or Off?
The EnableViewState property enables the ViewState property on the page. It is set to On to
allow the page to save the users input between postback requests of a Web page; that is, between
the Request and corresponding Response objects. When this property is set to Off, the page does
not store the users input during postback.
74. Which event determines that all the controls are completely loaded into memory?
The Page_Load event determines that all the controls on the page are fully loaded. You can also
access the controls in the Page_Init event; however, the ViewState property does not load
completely during this event.
75. What is the function of the CustomValidator control?
It provides the customize validation code to perform both client-side and server-side validation.

76. What is Role-based security?
In the Role-based security, you can assign a role to every user and grant the privilege according to
that role. A role is a group of principal that restricts a user's privileges. Therefore, all the organization
and applications use role-based security model to determine whether a user has enough privileges to
perform a requested task.
77. Which data type does the RangeValidator control support?
The data types supported by the RangeValidator control are Integer, Double, String, Currency, and
Date.
78. What are the HTML server controls in ASP.NET?
HTML server controls are similar to the standard HTML elements, which are normally used in HTML
pages. They expose properties and events that can be used programmatically. To make these controls
programmatically accessible, you need to specify that the HTML controls act as a server control by
adding the runat="server"attribute.
79. Why a SiteMapPath control is referred to as breadcrumb or eyebrow navigation control?
The SiteMapPath control displays a hierarchical path to the root Web page of the Web site.
Therefore, it is known as the breadcrumb or eyebrow navigation control.
80. Where is the ViewState information stored?
The ViewState information is stored in the HTML hidden fields.
81. Which namespaces are necessary to create a localized application?
The System.Globalization and System.Resources namespaces are essential to develop a
localized application.
82. What is the difference between an HtmlInputCheckBox control and
an HtmlInputRadioButton control?
You can select more than one HtmlInputCheckBox control from a group
of HtmlInputCheckBox controls; whereas, you can select only a
single HtmllnputRadioButton control from a group ofHtmlInputRadioButton controls.
83. What is the difference between HTML and Web server controls?
HTML controls are client-side controls; therefore, all the validations for HTML controls are performed
at the client side. On the other hand, Web server controls are server-side controls; therefore, all the
validations for Web server controls are performed at the server side.
84. Explain the AdRotator Control.

The AdRotator is an ASP.NET control that is used to provide advertisements to Web pages.
The AdRotatorcontrol associates with one or many advertisements, which randomly displays one by
one at a time when the Web page is refreshed. The AdRotator control advertisements are associated
with links; therefore, when you click on an advertisement, it redirects you to other pages.
The AdRotator control is associated with a data source, which is normally an xml file or a database
table. A data source contains all the information, such as advertisement graphics reference, link, and
alternate text. Therefore, when you use the AdRotator control, you should first create a data source
and then associate it with the AdRotator control.
85. What do you understand by the culture?
The culture denotes a combination of a language and optionally a region or a country. The contents of
a Web page of a multilingual Web site are changed according to the culture defined in the operating
system of the user accessing the Web page.
86. What is the difference between absolute expiration and sliding-time expiration?
The absolute expiration expires a cached item after the provided expiration time. The sliding time does
not expire the cached items because it increments the specified time.
87. What is the code-behind feature in ASP.NET?
The code-behind feature of ASP.NET enables you to divide an ASP.NET page into two files - one
consisting of the presentation data, and the second, which is also called the code-behind file,
consisting of all the business logic. The presentation data contains the interface elements, such as
HTML controls and Web server controls, and the code-behind contains the event-handling process to
handle the events that are fired by these controls. The file that contains the presentation data has the
.aspx extension. The code behind file has either the .cs extension (if you are using the programming
language C#) or the .vb (if you are using the programming language Visual Basic .NET) extension.
88. How can you check if all the validation controls on a Web page are valid and proper?
You can determine that all the validation controls on a Web page are properly working by writing code
in the source file of the Web page using a scripting language, such as VBScript or JavaScript. To do
this task, you have to loop across validators collection of pages and check the IsValid property of
each validation control on the Web page to check whether or not the validation test is successful.
89. Explain the validation controls. How many validation controls in ASP.NET 4.0?
Validation controls are responsible to validate the data of an input control. Whenever you provide any
input to an application, it performs the validation and displays an error message to user, in case the
validation fails.
ASP.NET 4.0 contains the following six types of validation controls:
 CompareValidator - Performs a comparison between the values contained in two controls.
 CustomValidator - Writes your own method to perform extra validation.
 RangeValidator- Checks value according to the range of value.

 RegularExpressionValidator - Ensures that input is according to the specified pattern or
not.
 RequiredFieldValidator - Checks either a control is empty or not.
 ValidationSummary - Displays a summary of all validation error in a central location.
90. What is difference between a Label control and a Literal control?
The Label control's final html code has an HTML tag; whereas, the Literal control's final html code
contains only text, which is not surrounded by any HTML tag.
91. How many types of Cookies are available in ASP.NET?
There are two types of Cookies available in ASP.NET:
 Session Cookie - Resides on the client machine for a single session until the user does not
log out.
 Persistent Cookie - Resides on a user's machine for a period specified for its expiry, such as
10 days, one month, and never.
The user can set this period manually.
92. What is the use of the Global.asax file?
The Global.asax file executes application-level events and sets application-level variables.
93. What are the Culture and UICulture values?
The Culture value determines the functions, such as Date and Currency, which are used to format data
and numbers in a Web page. The UICulture value determines the resources, such as strings or
images, which are loaded for a Web page in a Web application.
94. What is the difference between ASP session and ASP.NET session?
ASP does not support cookie-less sessions; whereas, ASP.NET does. In addition, the ASP.NET session
can span across multiple servers.
95. Which control will you use to ensure that the values in two different controls match?
You should use the CompareValidator control to ensure that the values in two different controls
match.
96. What is the difference between a page theme and a global theme?
A page theme is stored inside a subfolder of the App_Themes folder of a project and applied to
individual Web pages of that project. Global themes are stored inside the Themes folder on a Web
server and apply to all the Web applications on the Web server.
97. What do you mean by a neutral culture?

When you specify a language but do not specify the associated country through a culture, the culture
is called as a neutral culture.
98. What is the use of the <sessionState> tag in the web.config file?
The <sessionState> tag is used to configure the session state features. To change the default
timeout, which is 20 minutes, you have to add the following code snippet to the web.config file of an
application:<sessionState timeout="40"/>
99. Can you post and access view state in another application?
Yes, you can post and access a view state in other applications. However, while posting a view state in
another application, the PreviousPage property returns null.
100. Which method do you use to kill explicitly a users session?
The Session.Abandon() method kills the user session explicitly.
101. Which class is inherited when an ASP.NET server control is added to a Web form?
The System.Web.UI.WebControls class is inherited when an ASP.NET server control is added to a
Web form.
102. What events are fired when a page loads?
The following events fire when a page loads:
 Init() - Fires when the page is initializing.
 LoadViewState() - Fires when the view state is loading.
 LoadPostData() - Fires when the postback data is processing.
 Load() - Fires when the page is loading.
 PreRender() - Fires at the brief moment before the page is displayed to the user as HTML.
 Unload() - Fires when the page is destroying the instances of server controls.
103. Write three common properties of all validation controls.
Three common properties of validation controls are as follows:
 ControlToValidate - Provides a control to validate
 ErrorMessage - Displays an error message
 IsValid - Specifies if the control's validation has succeeded or not
 Text - Displays a text for validation control before validation
104. What are navigation controls? How many navigation controls are there in ASP.NET
4.0?

Navigation controls help you to navigate in a Web application easily. These controls store all the links
in a hierarchical or drop-down structure; thereby facilitating easy navigation in a Web application.
There are three navigation controls in ASP.Net 4.0.
 SiteMapPath
 Menu
 TreeView
105. What happens if an ASP.NET server control with event-handling routines is missing
from its definition?
The compilation of the application fails.
106. What are server-side comments?
Server-side comments are included in an ASP.NET page for the purpose of documentations as shown
in the following code snippet:
<%--This is an example of server-side comments --%>
The server-side comments begin with <%-- and end with --%>.
107. How can we provide the WebParts control functionality to a server control?
We can provide the WebParts controls functionality to a server control by setting
the CreateWebPart property of WebPartManger.
108. How do you prevent a validation control from validating data at the client end?
You can prohibit a validation control to validate data at the client side by setting
the EnableClientScriptproperty to False.
109. What is cross-page posting in ASP.NET?
The Server.Transfer() method is used to post data from one page to another. In this case, the
URL remains the same. However, in cross page posting, data is collected from different Web pages
and is displayed on a single page. To do so, you need to set the PostBackUrl property of the
control, which specifies the target page. In the target page, you can access
the PreviousPage property. For this, you need to use the@PreviousPageType directive. You can
access the controls of previous page by using the FindControl()method.
110. Which ASP.NET configuration options are supported in the ASP.NET implementation on
the shared Web hosting platform?
There are many ASP.NET configuration choices, which are not able to configure at the site, application,
or child directory level on the shared hosting environment. Some options can produce security,

performance, and stability problem to the server and therefore cannot be changed.
The following settings are the only ones that can be changed in the web.config file(s) of your Web
site:
 browserCaps
 clientTarget
 pages
 customErrors
 globalization
 authorization
 authentication
 webControls
 webServices
111. Explain the Application and Session objects in ASP.NET.
Application state is used to store data corresponding to all the variables of an ASP.NET Web
application. The data in an application state is stored once and read several times. Application state
uses theHttpApplicationState class to store and share the data throughout the application. You
can access the information stored in an application state by using the HttpApplication class
property. Data stored in the application state is accessible to all the pages of the application and is the
same for all the users accessing the application. The HttpApplicationState class provides a lock
method, which you can use to ensure that only one user is able to access and modify the data of an
application at any instant of time.
Each client accessing a Web application maintains a distinct session with the Web server, and there is
also some specific information associated with each of these sessions. Session state is defined in
the<sessionState> element of the web.config file. It also stores the data specific to a user
session in session variables. Different session variables are created for each user session. In addition,
session variables can be accessed from any page of the application. When a user accesses a page, a
session ID for the user is created. The session ID is transferred between the server and the client over
the HTTP protocol using cookies.
112. How will you differentiate a submaster page from a top-level master page?
Similar to a content page, a submaster page also does not have complete HTML source code;
whereas, a top-level master page has complete HTML source code inside its source file.
113. What are Web server controls in ASP.NET?
The ASP.NET Web server controls are objects on the ASP.NET pages that run when the Web page is
requested. Many Web server controls, such as button and text box, are similar to the HTML controls.
In addition to the HTML controls, there are many controls, which include complex behavior, such as
the controls used to connect to data sources and display data.
114. What is the difference between a HyperLink control and a LinkButton control?

A HyperLink control does not have the Click and Command events; whereas,
the LinkButton control has these events, which can be handled in the code-behind file of the Web
page.
115. What are the various ways of authentication techniques in ASP.NET?
There are various techniques in ASP.NET to authenticate a user. You can use one of the following ways
of authentication to select a built-in authentication provider:
 Windows Authentication - This mode works as the default authentication technique. It can
work with any form of Microsoft Internet Information Services (IIS) authentication, such as
Basic, Integrated Windows authentication (NTLM/Kerberos), Digest, and certificates. The
syntax of Windows authentication mode is given as follows: <authentication
mode="windows" />
 Forms Authentication - You can specify this mode as a default authentication mode by using
the following code snippet: <authentication mode="Forms"/>
 Passport - This mode works with Microsoft Passport authentication, as shown in the following
code snippet: <authentication mode = "Passport"/>
116. What are the different ways to send data across pages in ASP.NET?
The following two ways are used to send data across pages in ASP.NET:
 Session
 Public properties
117. What does the WebpartListUserControlPath property of
a DeclarativeCatalogPart control do?
The WebpartListUserControlPath property sets the route of the user defined control to
aDeclarativeCatalogPart control.
118. What do you mean by the Web Part controls in ASP.NET?
The Web Part controls are the integrated controls, which are used to create a Web site. These controls
allow the users to change the content, outlook, and state of Web pages in a Web browser.
119. What type of the CatalogPart control enables users to restore the Web Parts that
have been removed earlier by the user?
The PageCatalogPart control.
120. What is the use of web.config? What is the difference between machine.config and
web.config?
ASP.NET configuration files are XML-based text files for application-level settings and are saved with
the name web.config. These files are present in multiple directories on an ASP.NET Web application

server. Theweb.config file sets the configuration settings to the directory it is placed in and to all
the virtual sub folders under it. The settings in sub directories can optionally override or change the
settings specified in the base directory.
The difference between the web.config and machine.config files is given as follows:
 <WinDir>Microsoft.NETFramework<version>configmachine.config provides
default configuration settings for the entire machine. ASP.NET configures IIS to prohibit the
browser directly from accessing the web.config files to make sure that their values cannot be
public. Attempts to access those files cause ASP.NET to return the 403: Access Forbidden
error.
 ASP.NET uses these web.config configuration files at runtime to compute hierarchically a
sole collection of settings for every URL target request. These settings compute only once and
cached across further requests. ASP.NET automatically checks for changing file settings and do
not validate the cache if any of the configuration changes made.
121. Explain the concept of states in ASP.NET.
State is quite an innovative concept in Web development because it eliminates the drawback of losing
state data due to reloading of a Web page. By using states in a Web application, you can preserve the
state of the application either at the server or client end. The state of a Web application helps you to
store the runtime changes that have been made to the Web application. For example, as already
described earlier, a change in the data source of the Web application might be initiated by a user
when he/she selects and saves some products in the shopping cart.
If you are not using states, these changes are discarded and are not saved. You may think that the
whole concept of storing states is optional. However, under certain circumstances, using states with
applications is imperative. For example, it is necessary to store states for Web applications, such as an
e-commerce shopping site or an Intranet site of a company, to keep track of the requests of the users
for the items they have selected on the shopping site or the days requested for vacation on the
Intranet site.
122. Can we validate a DropDownList by RequiredFieldValidator?
Yes, we can validate a DropDownList by RequiredFieldValidator. To perform this validation, we
have to set the InitialValue property of RequiredFieldValidator control.
123. List the features of the Chart control.
The following are the features of the Chart control:
 Bounds a chart with any data source.
 Simple manipulation of chart data, such as copying, merging, grouping, sorting, searching,
and filtering.
 Support many statistical and financial formulas for data analysis.

 Provide advanced chart outlook, such as 2-D, 3-D, lighting, and perspective.
 Support events and customizations.
 Includes interactivity with Microsoft AJAX.
 Supports AJAX Content Delivery Network (CDN).
.NET Programming Concepts :
1. Define variable and constant.
A variable can be defined as a meaningful name that is given to a data storage location in the
computer memory that contains a value. Every variable associated with a data type determines what
type of value can be stored in the variable, for example an integer, such as 100, a decimal, such as
30.05, or a character, such as 'A'.
You can declare variables by using the following syntax:
<Data_type> <variable_name> ;
A constant is similar to a variable except that the value, which you assign to a constant, cannot be
changed, as in case of a variable. Constants must be initialized at the same time they are declared.
You can declare constants by using the following syntax:
const int interestRate = 10;
2. What is a data type? How many types of data types are there in .NET ?
A data type is a data storage format that can contain a specific type or range of values. Whenever you
declare variables, each variable must be assigned a specific data type. Some common data types
include integers, floating point, characters, and strings. The following are the two types of data types
available in .NET:
 Value type - Refers to the data type that contains the data. In other words, the exact value
or the data is directly stored in this data type. It means that when you assign a value type
variable to another variable, then it copies the value rather than copying the reference of that
variable. When you create a value type variable, a single space in memory is allocated to store
the value (stack memory). Primitive data types, such as int, float, and char are examples of
value type variables.
 Reference type - Refers to a data type that can access data by reference. Reference is a
value or an address that accesses a particular data by address, which is stored elsewhere in
memory (heap memory). You can say that reference is the physical address of data, where
the data is stored in memory or in the storage device. Some built-in reference types variables
in .Net are string, array, and object.

3. Mention the two major categories that distinctly classify the variables of C# programs.
Variables that are defined in a C# program belong to two major categories: value
type and reference type. The variables that are based on value type contain a value that is either
allocated on a stack or allocated in-line in a structure. The variables that are based on reference types
store the memory address of a variable, which in turn stores the value and are allocated on the heap.
The variables that are based on value types have their own copy of data and therefore operations
done on one variable do not affect other variables. The reference-type variables reflect the changes
made in the referring variables.
Predict the output of the following code segment:
int x = 42;
int y = 12;
int w;
object o;
o = x;
w = y * (int)o;
Console.WriteLine(w);
/* The output of the code is 504. */
4. Which statement is used to replace multiple if-else statements in code.
In Visual Basic, the Select-Case statement is used to replace multiple If - Else statements and in
C#, theswitch-case statement is used to replace multiple if-else statements.
5. What is the syntax to declare a namespace in .NET?
In .NET, the namespace keyword is used to declare a namespace in the code.
The syntax for declaring a namespace in C# is:
namespace UserNameSpace;
The syntax for declaring a namespace in VB is:
Namespace UserNameSpace
6. What is the difference between constants and read-only variables that are used in
programs?
Constants perform the same tasks as read-only variables with some differences. The differences
between constants and read-only are
Constants:
1. Constants are dealt with at compile-time.
2. Constants supports value-type variables.
3. Constants should be used when it is very unlikely that the value will ever change.

Read-only:
1. Read-only variables are evaluated at runtime.
2. Read-only variables can hold reference type variables.
3. Read-only variables should be used when run-time calculation is required.
7. Differentiate between the while and for loop in C#.
The while and for loops are used to execute those units of code that need to be repeatedly
executed, unless the result of the specified condition evaluates to false. The only difference between
the two is in their syntax. The for loop is distinguished by setting an explicit loop variable.
8. What is an identifier?
Identifiers are northing but names given to various entities uniquely identified in a program. The name
of identifiers must differ in spelling or casing. For example, MyProg and myProg are two different
identifiers. Programming languages, such as C# and Visual Basic, strictly restrict the programmers
from using any keyword as identifiers. Programmers cannot develop a class whose name is public,
because, public is a keyword used to specify the accessibility of data in programs.
9. What does a break statement do in the switch statement?
The switch statement is a selection control statement that is used to handle multiple choices and
transfer control to the case statements within its body. The following code snippet shows an example
of the use of theswitch statement in C#:
switch(choice)
{
case 1:
console.WriteLine("First");
break;
case 2:
console.WriteLine("Second");
break;
default:
console.WriteLine("Wrong choice");
break;
}
In switch statements, the break statement is used at the end of a case statement.
The break statement is mandatory in C# and it avoids the fall through of one case statement to
another.
10. Explain keywords with example.

Keywords are those words that are reserved to be used for a specific task. These words cannot be
used as identifiers. You cannot use a keyword to define the name of a variable or method. Keywords
are used in programs to use the features of object-oriented programming.
For example, the abstract keyword is used to implement abstraction and the inherits keyword is
used to implement inheritance by deriving subclasses in C# and Visual Basic, respectively.
The new keyword is universally used in C# and Visual Basic to implement encapsulation by creating
objects.
11. Briefly explain the characteristics of value-type variables that are supported in the C#
programming language.
The variables that are based on value types directly contain values. The characteristics of value-type
variables that are supported in C# programming language are as follows:
 All value-type variables derive implicitly from the System.ValueType class
 You cannot derive any new type from a value type
 Value types have an implicit default constructor that initializes the default value of that type
 The value type consists of two main categories:
 Structs - Summarizes small groups of related variables.
 Enumerations - Consists of a set of named constants.
12. Give the syntax of using the while loop in a C# program.
The syntax of using the while loop in C# is:
while(condition) //condition
{
//statements
}
You can find an example of using the while loop in C#:
int i = 0;
while(i < 5)
{
Console.WriteLine("{0} ", i);
i++;
}
The output of the preceding code is: 0 1 2 3 4 .
13. What is a parameter? Explain the new types of parameters introduced in C# 4.0.

A parameter is a special kind of variable, which is used in a function to provide a piece of information
or input to a caller function. These inputs are called arguments. In C#, the different types of
parameters are as follows:
 Value type - Refers that you do not need to provide any keyword with a parameter.
 Reference type - Refers that you need to mention the ref keyword with a parameter.
 Output type - Refers that you need to mention the out keyword with a parameter.
 Optional parameter - Refers to the new parameter introduced in C# 4.0. It allows you to
neglect the parameters that have some predefined default values. The example of optional
parameter is as follows:
 public int Sum(int a, int b, int c = 0, int d = 0); /* c and d is
optional */
 Sum(10, 20); //10 + 20 + 0 + 0
 Sum(10, 20, 30); //10 + 20 + 30 + 0
 Sum(10, 20, 30, 40); //10 + 20 + 30 + 40
 Named parameter - Refers to the new parameter introduced in C# 4.0. Now you can provide
arguments by name rather than position. The example of the named parameter is as follows:
 public void CreateAccount(string name, string address = "unknown", int
age = 0);
 CreateAccount("Sara", age: 30);
 CreateAccount(address: "India", name: "Sara");
14. Briefly explain the characteristics of reference-type variables that are supported in the
C# programming language.
The variables that are based on reference types store references to the actual data. The keywords that
are used to declare reference types are:
1. Class - Refers to the primary building block for the programs, which is used to encapsulate
variables and methods into a single unit.
2. Interface - Contains only the signatures of methods, properties, events, or indexers.
3. Delegate - Refers to a reference type that is used to encapsulate a named or anonymous
method.
15. What are the different types of literals?
A literal is a textual representation of a particular value of a type.
The different types of literals in Visual Basic are:
 Boolean Literals - Refers to the True and False literals that map to the true and false state,
respectively.
 Integer Literals - Refers to literals that can be decimal (base 10), hexadecimal (base 16), or
octal (base 8).
 Floating-Point Literals - Refers to an integer literal followed by an optional decimal point By
default, a floating-point literal is of type Double.

 String Literals - Refers to a sequence of zero or more Unicode characters beginning and
ending with an ASCII double-quote character.
 Character Literals - Represents a single Unicode character of the Char type.
 Date Literals - Represents time expressed as a value of the Date type.
 Nothing - Refers to a literal that does not have a type and is convertible to all types in the
type system.
The different types of literals in C# are:
 Boolean literals - Refers to the True and False literals that map to the true and false states,
respectively.
 Integer literals - Refers to literals that are used to write values of types int, uint, long, and
ulong.
 Real literals - Refers to literals that are used to write values of types float, double, and
decimal.
 Character literals - Represents a single character that usually consists of a character in quotes,
such as 'a'.
 String literals - Refers to string literals, which can be of two types in C#:
 A regular string literal consists of zero or more characters enclosed in double quotes,
such as "hello".
 A verbatim string literal consists of the @ character followed by a double-quote
character, such as @"hello".
 The Null literal - Represents the null-type.
16. What is the main difference between sub-procedure and function?
The sub-procedure is a block of multiple visual basic statements within Sub and End Sub statements.
It is used to perform certain tasks, such as changing properties of objects, receiving or processing
data, and displaying an output. You can define a sub-procedure anywhere in a program, such as in
modules, structures, and classes.
We can also provide arguments in a sub-procedure; however, it does not return a new value.
The function is also a set of statements within the Function and End Function statements. It is similar
to sub-procedure and performs the same task. The main difference between a function and a sub-
procedure is that sub-procedures do not return a value while functions do.
17. Determine the output of the code snippet.
int a = 29;
a--;
a -= ++a;
Console.WriteLine("The value of a is: {0}", a);
/* The output of the code is -1. */

18. Differentiate between Boxing and Unboxing.
When a value type is converted to an object type, the process is known as boxing; whereas, when an
object type is converted to a value type, the process is known as unboxing.
Boxing and unboxing enable value types to be treated as objects. Boxing a value type packages it
inside an instance of the Object reference type. This allows the value type to be stored on the garbage
collected heap. Unboxing extracts the value type from the object. In this example, the integer
variable i is boxed and assigned to object obj.
Example:
int i = 123;
object obj = i; /* Thi line boxes i. */
/* The object obj can then be unboxed and assigned to integer variable i: */
i = (int)obj; // unboxing
19. Give the syntax of using the for loop in C# code?
The syntax of using the for loop in C# code is given as follows:
for(initializer; condition; loop expression)
{
//statements
}
In the preceding syntax, initializer is the initial value of the variable, condition is the expression that is
checked before the execution of the for loop, and loop expression either increments or decrements
the loop counter.
The example of using the for loop in C# is shown in the following code snippet:
for(int i = 0; i < 5; i++)
Console.WriteLine("Hello");
In the preceding code snippet, the word Hello will be displayed for five times in the output window.

ASP.NET AJAX :
1. What is ASP.NET AJAX?
ASP.NET AJAX, mostly called AJAX, is a set of extensions of ASP.NET. It is developed by Microsoft to
implement AJAX functionalities in Web applications. ASP.NET AJAX provides a set of components that
enable the developers to develop applications that can update only a specified portion of data without
refreshing the entire page. The ASP.NET AJAX works with the AJAX Library that uses object-oriented
programming (OOP) to develop rich Web applications that communicate with the server using
asynchronous postback.
2. What is the difference between synchronous postback and asynchronous postback?
The difference between synchronous and asynchronous postback is as follows:
 Asynchronous postback renders only the required part of the page; whereas, synchronous
postback renders the entire page for any postback.
 Asynchronous postback executes only one postback at a time, that is, if you have two buttons
doing asynchronous postback, the actions will be performed one by one; whereas,
synchronous postback executes all the actions at once.
 Asynchronous postback only modifies the update panel that raises the postback; whereas,
synchronous postback modifies the entire page.
3. What technologies are being used in AJAX?
AJAX uses four technologies, which are as follows:
 JavaScript
 XMLHttpRequest
 Document Object Model (DOM)
 Extensible HTML (XHTML) and Cascading Style Sheets (CSS)
4. Why do we use the XMLHttpRequest object in AJAX?
The XMLHttpRequest object is used by JavaScript to transfer XML and other text data between client
and server. The XMLHttpRequest object allows a client-side script to perform an HTTP request. AJAX
applications use the XMLHttpRequest object so that the browser can communicate to the server
without requiring a postback of the entire page. In earlier versions of Internet Explorer, MSXML

ActiveX component is liable to provide this functionality; whereas, Internet Explorer 7 and other
browsers, such as Mozilla Firefox,XMLHttpRequest is not liable to.
5. How can we get the state of the requested process?
XMLHttpRequest get the current state of the request operation by using the readyState property.
This property checks the state of the object to determine if any action should be taken.
The readyState property uses numeric values to represent the state.
6. What are the different controls of ASP.NET AJAX?
ASP.NET AJAX includes the following controls:
 ScriptManager
 ScriptManagerProxy
 UpdatePanel
 UpdateProgress
 Timer
7. What are the new features included in the Microsoft AJAX library?
The Microsoft AJAX library is a client-based JavaScript library that is compatible with all modern
browsers and offers a lot of functionality as compared to JavaScript. This library is released with new
features and fully supports ASP.NET 4.0'. The new features included in the Microsoft AJAX library are
as follows:
 Imperative syntax - Supports simple imperative syntax that is used to create and manage
controls.
 Script loader - Retrieves all scripts that are needed by one or more client component or
control automatically and executes the scripts in the order in which they are received.
 Client data access - Supports to access client data and display by client data control and
client template.
 Client datacontext - Supports read and write permission to data from a database.
 The AdoNetDataContext class - Enables you to easily interact with an ADO.NET Data
Services service.
 jQuery integration - Helps to access the elements in your Web pages, work with client-side
events, enable visual effects, and make it easier to use AJAX in your applications.
8. Explain the Step property of the NumericUpDownExtender control.
The Step property sets the steps for numeric increment and decrement. The default value is 1.
9. What are the new features of ASP.NET AJAX 4.0?
ASP.NET 4.0 AJAX includes several new features that provide more functionality to a user. These
features are as follows:

 Support for live data binding.
 Support for client-side template rendering.
 Support for declarative instantiation of client components.
 Support for using the observer pattern on JavaScript objects and arrays.
 Support for invoking ADO.NET data services and data contexts.
 Support for the DataView control.
10. Why do we use the UpdateProgress control in AJAX?
The UpdateProgress control is somewhat related to the UpdatePanel control.
The UpdateProgress control enables you to design a user-friendly interface when a Web page
consists of a number of UpdatePanel controls for partial-page rendering.
The UpdateProgress control makes you aware of the status information about the partial-page
updates in theUpdatePanel control.
11. What is JSON?
JSON is an abbreviation of JavaScript Object Notation. It is a safe and reliable data interchange format
in JavaScript, which is easy to understand not only for the users but also for the machines.
12. How many validation controls are available in ASP.NET AJAX 4.0?
The following validation controls are available in ASP.NET AJAX 4.0:
 FilteredTextBoxExtender - Enables you to apply filtering to a text box.
 MaskedEditExtender and MaskedEditValidator - Restricts a user to enter only a certain
pattern of characters in the TextBox by applying a mask to the input.
 ValidatorCalloutExtender - Attaches to the ASP.NET validators so that the error
messages are not displayed as a simple text but as a balloon-style ToolTip.
 NoBot - Prevents the spam/bot from filling the input forms automatically and uses the
Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA),
which is a type of challenge-response test to ensure that the response is not generated by the
computer.
 PasswordStrengthExtender - Measures the strength of the password text entered within
the text box by validating with the different strength specified parameters
13. Explain the limitations of AJAX.
The following are the limitations of AJAX:
 It is difficult to bookmark a particular state of the application.
 Function provided in the code-behind file do not work because the dynamic pages cannot
register themselves on browsers history engine automatically.
 If JavaScript is disabled, then AJAX is not able to perform any work.
 Response time may be slow because different controls of a page are loaded at different time.

14. What are the differences between AJAX and JavaScript?
The differences between AJAX and JavaScript are given as follows:
 AJAX sends request to the server and does not wait for the response. It performs other
operations on the page during that time. JavaScript make a request to the server and waits for
response.
 AJAX does not require the page to refresh for downloading the whole page while JavaScript
manages and controls a Web page after being downloaded.
 AJAX minimizes the overload on the server since the script needs to request once while
JavaScript posts a request that updates the script every time.
15. Explain the UpdatePanel control.
The UpdatePanel control specifies the portions of a Web page that can be updated together. As
theUpdatePanel control refreshes only a selected part of the Web page instead of refreshing the
entire page with a postback, you get more flexibility to create rich and client-centric Web applications.
Refreshing a selected part of the Web page is referred as partial-page update. You can add one or
moreUpdatePanel control in the Web page, which automatically participates in partial-page update
without custom client script. The UpdatePanel control uses the UpdatePanel class to support the
partial-page rendering.
16. What does the DynamicPopulateExtender control do?
The DynamicPopulateExtender control populates the contents of a control dynamically. It enables
you to send an asynchronous call to the server that dynamically populates the contents of a control.
TheDynamicPopulateExtender control replaces the contents of a control with the result of a Web
service or page method call.
17. What does the MinimumPrefixLength property of the AutoCompleteExtender control
do?
The MinimumPrefixLength property sets the minimum number of characters that must be entered
before getting suggestions from the Web service.
18. What is the importance of client-side libraries?
Client-side libraries contain built-in code to make asynchronous calls over XMLHTTP. These libraries
automatically handle browser compatibility issues. These libraries are based on a programming model
similar to ASP.NET.
19. Can we call server-side code from JavaScript?
Yes, page methods and Web services are the two techniques to call the server-side code from
JavaScript.

20. What are the components of the ASP.NET AJAX architecture?
You can divide the ASP.NET AJAX architecture into two components - AJAX client architecture and
AJAX server architecture.
21. Describe AJAX Control Extender Toolkit.
AJAX Control Toolkit is a set of extenders that are used to extend the functionalities of the ASP.NET
controls. The extenders use a block of JavaScript code to add new and enhanced capabilities to the
ASP.NET controls. AJAX Control Toolkit is a free download available on the Microsoft site. You need to
install this toolkit on your system before using extenders.
22. Explain the need of the Timer control in AJAX.
The Timer control is used with an UpdatePanel control to allow partial-page updates at a specified
interval. It is mostly used when a periodically partial-page update for one or
more UpdatePanel controls is required without refreshing the entire page.
The Timer control is a server control that sets a JavaScript component in the Web page.
The interval property of the Timer control specifies time in milliseconds. Similar to
the UpdatePanel control, the Timer control also requires an instance of the ScriptManager control
in the Web page.
When the Timer control initiates a postback, the Tick event is raised on the server for which you can
provide an event handler to perform the actions when the page is submitted to the server.
The Tick event occurs when the time specified in the interval property has elapsed and the page is
posted on the server. You can add one or more Timer controls on a Web page. Usually the entire page
requires only a single Timer control; however, you can use multiple Timer controls, if
the UpdatePanel controls are being updated at different intervals.
23. List the different states of XMLHttpRequest with their description.
The different states of the XMLHttpRequest object are as follows:
 Uninitialized - Refers to the state when the object has not been initialized.
 Open - Refers to the state when the object has been created; however, the send function has
not been invoked.
 Sent -Refers to the state when the send function is invoked; however, the status and headers
are not available.
 Receiving - Refers to the state when the process is receiving data.
 Loaded - Refers to the state when the procedure is completed and the entire data is
available.
24. Can we nest the UpdatePanel controls?
Yes, we can nest the UpdatePanel control.

25. What is the role of the ScriptManagerProxy control?
A Web page cannot contain more than one ScriptManager control. You can use
the ScriptManagerProxycontrol to add scripts to other pages; however to perform such an
operation, you need to work with a master page that contains the ScriptManager control. If you
have only few pages that need to register to a script or a Web service, then you should remove these
pages from the ScriptManager control and add them as individual pages by using
the ScriptManagerProxy control. If you include the scripts on the master page by
theScriptManager control, then the items get downloaded on each page that extends the master
page, even if they are not necessary.
26. What is the work of the ConformOnFormSubmit property in
the ConfirmButtonExtender control?
The ConformOnFormSubmit property determines whether or not the confirm dialog box should wait
when the form is submitted for display.
27. What is the syntax to create AJAX objects?
AJAX uses the following syntax to create an object:
var myobject = new AjaxObject("page path");
The page path is the URL of the Web page containing the object that you want to call. The URL must
be of the same domain as the Web page.
28. Is there any difference between HTML and XHTML?
Extensible HTML (XHTML) is a markup language that provides the mixture expressions of HTML and
XML. XHTML is a flexible markup language that enables automated processing by standard XML tools,
which was difficult in HTML.
29. What are the requirements to run ASP.NET AJAX applications on a server?
AJAX is a built-in functionality of .NET Framework 4.0. Therefore, you can run an AJAX application by
just installing Microsoft Visual Studio 2010. However, to use extenders in your applications, you are
required to install AJAX Control Toolkit and copy the AjaxControlToolkit.dll file to the Bin
directory of your application.
30. Describe the situations in which AJAX should not be used.
You should not use AJAX if:
 You want the page to show in a search engine, such as Google, because WebCrawler does not
execute JavaScript code.
 The browser does not support JavaScript.
 You want to create a secure application.

31. What is the use of the ScriptManager control in AJAX?
The ScriptManager control is a core control that performs a key role in implementing the ASP.NET
AJAX functionality. It helps to use JavaScript for the Microsoft AJAX Library. It should be noted that
AJAX Library on a Web page can only be used if the Web page contains the ScriptManager control.
This control makes use of theScriptManager class to maintain the AJAX script libraries and script
files. It allows for partial page rendering, Web service calls, and use of ASP.NET AJAX Client Library by
rendering the AJAX Library scripts to the browser.
32. How can you find out that an AJAX request has been completed?
You can find out that an AJAX request has been completed by using the readyState property. If the
value of this property equals to four, it means that the request has been completed and the data is
available.
33. Is it possible to use multiple ScriptManager controls on a Web page?
No, it is not possible.
34. What are the new controls introduced in ASP.NET AJAX Control Toolkit?
The following controls are introduced with the new version of AJAX Control Toolkit:
 SeaDragonExtender control - Refers to the control that is used to deeply zoom the images.
You can zoom in or out the image or the particular portion of the image by using the mouse.
You can also create a menu over the Seadragon control. This control is helpful when you want
to analyze the image closely.
 AsyncFileUploadExtender control - Refers to the control that provides the facility to
upload and save the files on the server asynchronously. You can check the outcome either at
the server or client side.
35. Briefly describe ASP.NET AJAX Framework.
ASP.NET AJAX Framework provides a platform where developers can develop such type of applications
that use the AJAX concept. The AJAX provides the collection of technologies to create dynamic pages
at the client side. The JavaScript requests are responsible to retrieve data from the server or send
data to the server. Even some processing at server also requires handling requests, such as searching
and storing of data. These tasks are achieved more easily using the AJAX Framework.
AJAX Framework is completely devoted to process requests. The objective of the AJAX engine is to
reduce the delays that the user notices while performing a postback to the server. AJAX Framework
allows JavaScript functions to send requests to server at the client side. On the other side, it allows
the server to process the client's request, searches data, and responds the result to the browser.
36. Is the AjaxControlToolkit.dll file installed in the Global Assembly Cache?
No, you have to copy this file to the Bin folder of your application.

37. What are the different ways to pass parameters to the server?
We can pass parameters to the server using either the GET or POST method. The following code
snippets show the example of both the methods:
 Get: XmlHttpObject.Open("GET", "file1.txt", true);
 Post: XmlHttpObject.Open("POST", "file2.txt", true);
38. What are the extender controls?
The extender controls uses a block of JavaScript code to add new and enhanced capabilities to
ASP.NET. The developers can use a set of sample extender controls through a separate download -
AJAX Control Toolkit (ACT).
39. Describe the AccordionExtender control.
The AccordionExtender control is similar to the CollapsiblePanelExtender control. It allows
you to group multiple collapsible panels in a single control. At the same time, it also manages the
collapsed and expanded state of each panel; therefore, expanding one panel at a time. In other
words, the AccordionExtender control does not support expanding two or more panels
simultaneously. Instead, the header templates of all the panels are always visible so that you can click
on any of them to display the hidden contents. By default, theAccordionExtender control opens
with one panel as expanded.

.NET Assemblies :
1. What is an assembly?
Assemblies are the basic building blocks required for any application to function in the .NET realm.
They are partially compiled code libraries that form the fundamental unit of deployment, versioning,
activation scoping, reuse, and security. Typically, assemblies provide a collection of types and
resources that work together to form a logical unit of functionality. They are the smallest deployable
units of code in .NET. Compared to the executable files assemblies are far more reliable, more secure,
and easy to manage. An assembly contains a lot more than the Microsoft Intermediate Language
(MSIL) code that is compiled and run by the Common Language Runtime (CLR). In other words, you
can say that an assembly is a set of one or more modules and classes compiled in MSIL, and metadata
that describes the assembly itself, as well as the functionalities of the assembly classes.
2. Name the different components of an assembly.
An assembly is a logical unit that is made up of the following four different types of components:
 Assembly manifest
 MSIL source code
 Type metadata
 Resources
3. What are the different types of assemblies? Explain them in detail.
The following are the two types of assemblies:
 Private Assembly - Refers to the assembly that is used by a single application. Private
assemblies are kept in a local folder in which the client application has been installed.
 Public or Shared Assembly - Refers to the assembly that is allowed to be shared by multiple
applications. A shared assembly must reside in Global Assembly Cache (GAC) with a strong
name assigned to it.
For example, imagine that you have created a DLL containing information about your business logic.
This DLL can be used by your client application. In order to run the client application, the DLL must be
included in the same folder in which the client application has been installed. This makes the assembly
private to your application. Now suppose that the DLL needs to be reused in different applications.
Therefore, instead of copying the DLL in every client application folder, it can be placed in the global
assembly cache using the GAC tool. These assemblies are called shared assemblies.
4. Can one DLL file contain the compiled code of more than one .NET language?
No, a DLL file can contain the compiled code of only one programming language.

5. What is the maximum number of classes that can be contained in a DLL file?
There is no limit to the maximum number of classes that can be contained in a DLL file.
6. What is a satellite assembly?
Satellite assemblies are assemblies that are used to deploy language and culture specific resources for
an application. In an application, a separate product ID is assigned to each language and a satellite
assembly is installed in a language specific sub-directory.
7. Is versioning applicable to private assemblies?
No, versioning is not applicable to private assemblies as these assemblies reside in their individual
folders. Versioning can be applied to GAC only.
8. What is metadata?
An assembly metadata describes every data type and member defined in the code. It stores the
description of an assembly, such as name, version, culture, public key of an assembly along with the
types exported, other assemblies dependent on this assembly, and security permissions needed to run
the application. In addition, it stores the description of types, such as the name, visibility, base class,
interfaces implemented, and members, such as methods, fields, properties, events, and nested types.
It also stores attributes. Metadata is stored in binary format. Therefore, metadata of an assembly is
sharable among applications that execute on various platforms. It can also be exported to other
applications to give information about the services and various features of an application.
9. What is Assembly Manifest?
Assemblies maintain all their information in a special unit called the manifest. Every assembly has a
manifest.
The followings are the contents of an Assembly Manifest:
 Assembly name - Represents a text string that specifies the assembly's name.
 Version number - Represents a major and minor version number, as well as a revision and
build number. The CL.R makes use of these numbers to enforce version policy.
 Culture - Represents information of the culture or language, which the assembly supports. An
assembly is a container of only resources containing culture- or language-specific information.
 Strong name information - Represents the public key from the publisher, if a strong name
is assigned to an assembly.
 List of all files in the assembly - Represents a hash of each file contained in the assembly
and a file name.
 Type reference information - Represents the information used at the runtime to map a type
reference to the file that contains its declaration and implementation.
 Information on referenced assemblies - Represents a list of other assemblies that are
statically referenced by the assembly. Each reference includes the names of dependent

assemblies, assembly metadata (version, culture, operating system, and so on), and public
key, if the assembly is strong named.
10. What is the value of the Copy Local property when you add an assembly in the GAC?
False.
11. What is Native Image Generator?
The Native Image Generator (Ngen.exe) is a tool that creates a native image from an assembly and
stores that image to native image cache on the computer. Whenever, an assembly is run, this native
image is automatically used to compile the original assembly. In this way, this tool improves the
performance of the managed application by loading and executing an assembly faster.
Note that native images are files that consist of compiled processor-specific machine code. The
Ngen.exe tool installs these files on to the local computer.
12. Name the MSIL Disassembler utility that parses any .NET Framework assembly and
shows the information in human readable format
The Ildasm.exe utility.
13. What is the significance of the Strong Name tool?
The Strong Name utility (sn.exe) helps in creating unique public-private key pair files that are called
strong name files and signing assemblies with them. It also allows key management, signature
generation, and signature verification.
14. How can different versions of private assemblies be used in the same application
without a re-build?
You can use different versions of private assemblies in the same application without a re-build by
specifying the assembly version in the AssemblyInfo.cs or AssemblyInfo.vb file.
15. What is Global Assembly Cache (GAC) ?
GAC is a central repository (cache) in a system in which assemblies are registered to share among
various applications that execute on local or remote machines. .NET Framework provides the GAC tool
(gacutil.exeutility), which is used to view and change the content of GAC of a system. Adding new
assemblies to GAC and removing assemblies from GAC are some of the tasks that can be performed
by using the gacutil.exe utility. GAC can contain multiple versions of the same .NET assembly. CLR
checks GAC for a requested assembly before using information of configuration files.
The gacutil.exe /i <assembly name> - is the command that is used to install an assembly in
GAC. Users use the Command Prompt of Visual Studio to install an assembly in GAC by using this
command.

You can see all the assemblies installed in the GAC using the GAC viewer, which is located at
the <WinDrive>:<WinDir>assembly directory, where <WinDir> is windows in Windows XP or
windows in Windows Vista or WinNT in Windows 2000. Apart from the list of assemblies, the assembly
viewer also shows relevant information, such as the global assembly name, version, culture, and the
public key token.
16. Where is the information regarding the version of the assembly stored?
Information for the version of assembly is stored inside the assembly manifest.
17. Discuss the concept of strong names.
Whenever, an assembly is deployed in GAC to make it shared, a strong name needs to be assigned to
it for its unique identification. A strong name contains an assembly's complete identity - the assembly
name, version number, and culture information of an assembly. A public key and a digital signature,
generated over the assembly, are also contained in a strong name. A strong name makes an assembly
identical in GAC.
18. What is the difference between .EXE and .DLL files?
EXE
1. It is an executable file, which can be run independently.
2. EXE is an out-process component, which means that it runs in a separate process.
3. It cannot be reused in an application.
4. It has a main function.
DLL
1. It is Dynamic Link Library that is used as a part of EXE or other DLLs. It cannot be run
independently.
2. It runs in the application process memory, so it is called as in-process component.
3. It can be reused in an application.
4. It does not have a main function.
19. Which utility allows you to reference an assembly in an application?
An assembly can be referenced by using the gacutil.exe utility with the /r option. The /r option
requires a reference type, a reference ID, and a description.
20. The AssemblyInfo.cs file stores the assembly configuration information and other
information, such as the assembly name, version, company name, and trademark
information. (True/False).
True.

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