.NET Framework Interview Questions

.NET Framework Interview Questions

                          

1. What are Web services?

·        Web services are functions exposed by server-side applications.

·        They are programmable units that other applications (and Web services) can access over the Internet. 

2. What are session management techniques in .NET?

There are three different techniques of managing session in ASP.NET
1.InProc.
Session state is stored locally in memory of ASP.NET worker process.

2.StateServer 
Session state is stored outside ASP.NET worker process and is managed by Windows service.

Location of this service is specified by stateConnectionString attribute.

3.SQLServer 
Session state is stored outside ASP.NET worker process in SQL Server database. Location of this database is represented by sqlConnectionString attribute.

3. What is MVC (Model View Controller) pattern?

·        The Model-View-Controller (MVC) pattern separates the modeling of the domain, the presentation, and the actions based on user input into three separate classes
Model.

·        The model manages the behavior and data of the application domain, responds to requests for information about its state (usually from the view), and responds to instructions to change state (usually from the controller). 

·        View. The view manages the display of information. 

·        Controller. The controller interprets the mouse and keyboard inputs from the user, informing the model and/or the view to change as appropriate. 

4. How to use trace in libraray classes (like BAL, DAL)?

                                                   

·        Use following code to use Trace.Warn, Trace.Write etc. 

·        System.Web.HttpContext.Current.Trace

5. What is gacutil.exe?

·        It's a command to install the assembly into the Global Assembly Cache.

6. What is boxing and unboxing?

Converting a value type to reference type is called Boxing and Converting reference type of value type is Unboxing. 

int i = 1; 

object o = i; // boxing 

int j = (int) o; // unboxing

7. Difference between Response.Expires and Response.ExpiresAbsolute?

Response.Expires
This property specifies the number of minutes before a page cached in the browser expires ie. if the user returns to the same page before the specified number of minutes the cached version of the page is displayed.
<% Response.Expires = minutes %>

Response.ExpiresAbsolute
Using this property we can set the date and/or time at which page cached in the browser expires.
<% Response.ExpiresAbsolute=#May 15, 1999 18:00:00# %>

8. What is CLR (Common Language Runtime)?

This is an execution engine for .NET Framework application. It provides a number of services including
1. Code Management
2. Application memory isolation
3. Verification of type safety
4. Conversion of IL to native code.
5. Access to meta data
6. Managing memory for managed objects
7. Enforcement of code access security
8. Exception handling, including cross-language exceptions.
9. Inter operation between managed code, COM objects and pre-existing DLLs (Unmanaged code and data)
10. Automation of object layout
11. Support for developer services (profiling, debugging etc.)

9. When to use String and StringBuilder class?

·        Use the String class to concat, join or format methods to join multiple items in a single statement. 

·        Use StringBuilder class to create dynamic strings.

10. String is a value type or reference type?

String is a reference type variable.

11. List few ValueTypes variables.

Below are all ValueTypes variables. 

1.     System.SByte, 

2.     System.Byte 

3.     System.Int16 

4.     System.Int32 

5.     System.Int64 

6.     System.Single 

7.     System.Double 

8.     System.Decimal

9.     System.Char 

10.                        System.Boolean 

11.                        System.DateTime

12. What is the use of RCW & CCW?

·        RCW : Runtime Collable Wrapper takes a COM component, wrap it up and allows .NET client to consume it. 

·        CCW: COM Collable Wrapper wraps a .NET object for consumption by COM client

13. What is StringCollection?

·        StringCollection is a simple resizable collection of strings 

14. Where reference and value types variables are stored?

·        All reference type variables are stored in heap (Random) and all value types variables are stored in stack (Sequential).

15. What is Singleton pattern?

·        Singleton pattern ensures a class has only one instance & provide a global point of access to it.

·        It is achieved by declaring a static variable for the class & checking for null before actually instantiating it.

16. What is CTS?

·        CTS (Common Type System) is a rich type system, build into the common language runtime that supports the types and operations found in most of the programming languages.

·        The common type system supports the complete implementation of a wide range of programming language.

17. What is CLS?

·        CLS (Common Language Specification) is a set of constructs or constraints that serves as a guide for library writers and compiler writers.

·        It allows libraries to be fully usable from any language supporting the CLS, and for those languages to integrate with each other.

·        The CLS is a subset of common type system.

·         The common language specifications is also important to application developers wh are writing code that will be used by other developers.

18. What is MSIL?

·        MSIL (Microsoft Intermediate Language) is a CPU-Independent instructions set into which .NET Framework programs are compiled.

·        It contains instructions for loading, storing, initializing and calling methods on objects.

19. What is Satellite Assembly?

·        It is a often used to deploy language specific resources for an application.

·        These assemblies work in side-by-side execution because the application has a separate product ID for each language & installed satellite assemblies in a language specific sub-directory.

·        When uninstalling, the application removes only the satellite assemblies associated within a give language & .NET Framework version.

20. What is RSS?

·        RSS (Really Simple Syndication/Rich Site Summary) is a light weight XML format for distributing news headlines or site summary & other contents of the website.