Asp.Net Framework Question Ans

1) what is .NET ?

.Net is a framework where we can develop different applications in a single environment using different type of languages


2)What is .NET Framework?


The .NET Framework has two main components: the common language runtime and

the .NET Framework class library.

You can think of the runtime as an agent that manages code at execution time,

providing core services such as memory management, thread management, and

remoting, while also enforcing strict type safety and other forms of code accuracy that

ensure security and robustness.

The class library, is a comprehensive, object-oriented collection of reusable types that

you can use to develop applications ranging from traditional command-line or

graphical user interface (GUI) applications to applications based on the latest

innovations provided by ASP.NET, such as Web Forms and XML Web services.


3) What is CLR?

The CLS is simply a specification that defines the rules to support language integration

in such a way that programs written in any language, yet can interoperate with one

another, taking full advantage of inheritance, polymorphism, exceptions, and other

features.

4) What are Generics in .Net framework 2.0?

Generics are related to the idea of Templates in C++. They permit classes, structs, interfaces, delegates, and methods to be parameterized by the types of data they store and manipulate. Without generics, general purpose methods or data structures (like Lists, Stacks, etc.) typically use the built-in Object type to store data of any type. While the use of the built-in Object type makes the implementation very flexible, it has drawbacks with regards to Performance and Type Safety.


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

EnableViewState turns on the automatic state management feature that enables server controls to re-populate their values on a round trip without requiring you to write any code. This feature is not free however, since the state of a control is passed to and from the server in a hidden form field. You should be aware of when ViewState is helping you and when it is not.

6)What are the different modes for the sessionstates in the web.config file?

Off: Indicates that session state is not enabled.

Inproc: Indicates that session state is stored locally.

StateServer: Indicates that session state is stored on a remote server.

SQLServer: Indicates that session state is stored on the SQL Server.

7) Conditional Boating?
Bloating is an activity of performance improvement which is basically introduced in AJAX controls. The property UpdateMode is responsible for bloating for example the control updatepanel if you set UpdateMode Conditional then that clears your query.

8) What is the difference between Dataset.clone() and Dataset.copy()?
Using Dataset.clone() creates new instance of the same object.
Using Dataset.copy() copies content of data to another object wihtout creating new instance.

9) What is the difference between EVENTS and FUNCTIONS?
Event represents an action that is done to an object whereas Function represents an action that the object itself is doing.

10) what is the difference between application state and caching?
Application variable is the global variable specific to application but a
caching variable is specifc to page and time out.
Application variables exist as long as the application is alive. Whereas the cache has the Property of timeout which allows us to control the duration of the Objects so cached.
Another usefulness in caching is that we can define the way we cache our output since caching can be done in 3 ways -
a) Full Page - defined in page directrive
b) Partial Page - Eg - .ascx control
c) Data / Programatic caching. using the Properties of Cache object such as Cache.Insert .

NOTE:
Caching variable is specifc to page and time out
Application variable is the global variable specific to application

11) What is a Webcontrol?

Serves as the base class that defines the methods properties and events common to all controls in the System.Web.UI.WebControls namespace
A control is an object that can be drawn on to the Web Form to enable or enhance user interaction with the application. Examples of these controls include the TextBoxes Buttons Labels Radio Buttons etc. All these Web server controls are based on the System.Web.UI.Control class


12) Where do the Cookie State and Session State information be stored?

While executing the dynamic web page at the end of execution the value of session variables is calculated compressed and transmitted to the client via a Cookie. At this stage the state resides entirely and only on the client file system (or RAM).

Cookie Information will be stored in a txt file on client system under a
folder named Cookies. Search for it in your system you will find it.

Coming to Session State

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

In case of InProc Session Info will be stored inside the process where our
application is running.

In case of StateServer Session Info will be stored using ASP.NET State Service.

In case of SQLServer Session info will be stored inside Database. Default DB
which will be created after running InstallSQLState Script is ASPState.

13) what is difference between key word &key filter?

The KeyFilter property is a new property that was added to control. Handling the KeyDown /KeyUp / KeyPress generates a callback on every key down which can be a great overhead if all you want is to handle a specific key down. That is way the new KeyFilter property was added. Basically it allows to define a filter which helps VWG generate callbacks only when you really need it. In the following sample code we have demonstrated the implementation of adding arrow behaviors to a set of text boxes which allows navigating between the fields.

Keyword is the reserved default words used by the language.


14) What is the difference between mechine.config and web.config?
Every asp.net application has web.cofig file. the settings given in this file is implied to that particular application only.But the settings given in machine.config file is implied to whole system.
Basically Machine.config file content the configuration setting for a particullar machine and Web.config file is used to store configure a particular web application. On any system there will be only one Machine.config file but Web.config file can number of time as per web application

15) What is the difference between Response.Redirect and Server.Transfer?

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

Response.Redriect means it can redirect the page which is located inside the application directory.server.transfer means it goes to another directory of the file.

Server.Transfer() send the request to server
Response.Redirect() sends the request to Browser
So If the Request is made for the location outside the Server it fails. so you need to use Respons.Redirect().

16) What is use of DataAdapater? and is it possible to add data from data reader directly to a dataset or a datatable?

DataAdapters purpose is to perform database queries and create dataTables containing the query results. Its also capable of writing changes made to the datataTables back to the database.

DataAdapter acts as a go-between providing a layer of abstraction between DataSet and the Physical Data sorce.


17) how many kinds of web services are there?

1) .Net web services

2) Java web services

3) brand X web services (built on SOAP)


18) what is name space for xml in asp.net

NameSpace : System.XML
Filde: System.Xml.dll


19) difference between remoting and web service in .net?explain with an example

in web service when the function which resides in the server is called by client side the message protocol used is soap and transfer protocol used is http.so all the message is first converted to xml format and serializes and use http transfer protocol for transfer to the server and again in server it gets deserialized and from the xml file it gets information about which fun ction is called by the client and what r the parameter.and agai return the value in xml format.As the message is passed in xml format it is platform independent

Remoting lets us enjoy the same power of web services when the platform is same.we can connect to the server directly over TCP and send binary data without having to do lots of conversion.


20) Explain the life cycle of an ASP .NET page.

Events in ASP.Net 1.1 & 2.0 :-



Application: BeginRequest
Application: PreAuthenticateRequest
Application: AuthenticateRequest
Application: PostAuthenticateRequest
Application: PreAuthorizeRequest
Application: AuthorizeRequest
Application: PostAuthorizeRequest
Application: PreResolveRequestCache
Application: ResolveRequestCache
Application: PostResolveRequestCache
Application: PreMapRequestHandler
Page: Construct
Application: PostMapRequestHandler
Application: PreAcquireRequestState
Application: AcquireRequestState
Application: PostAcquireRequestState
Application: PreRequestHandlerExecute
Page: AddParsedSubObject
Page: CreateControlCollection
Page: AddedControl
Page: AddParsedSubObject
Page: AddedControl
Page: ResolveAdapter
Page: DeterminePostBackMode
Page: PreInit
Control: ResolveAdapter
Control: Init
Control: TrackViewState
Page: Init
Page: TrackViewState
Page: InitComplete
Page: LoadPageStateFromPersistenceMedium
Control: LoadViewState
Page: EnsureChildControls
Page: CreateChildControls
Page: PreLoad
Page: Load
Control: DataBind
Control: Load
Page: EnsureChildControls
Page: LoadComplete
Page: EnsureChildControls
Page: PreRender
Control: EnsureChildControls
Control: PreRender
Page: PreRenderComplete
Page: SaveViewState
Control: SaveViewState
Page: SaveViewState
Control: SaveViewState
Page: SavePageStateToPersistenceMedium
Page: SaveStateComplete
Page: CreateHtmlTextWriter
Page: RenderControl
Page: Render
Page: RenderChildren
Control: RenderControl
Page: VerifyRenderingInServerForm
Page: CreateHtmlTextWriter
Control: Unload
Control: Dispose
Page: Unload
Page: Dispose
Application: PostRequestHandlerExecute
Application: PreReleaseRequestState
Application: ReleaseRequestState
Application: PostReleaseRequestState
Application: PreUpdateRequestCache
Application: UpdateRequestCache
Application: PostUpdateRequestCache
Application: EndRequest
Application: PreSendRequestHeaders
Application: PreSendRequestContent


------------

Page_Init -- Page Initialization

LoadViewState -- View State Loading

LoadPostData -- Postback data processing

Page_Load -- Page Loading

RaisePostDataChangedEvent -- PostBack Change Notification

RaisePostBackEvent -- PostBack Event Handling

Page_PreRender -- Page Pre Rendering Phase

SaveViewState -- View State Saving

Page_Render -- Page Rendering

Page_UnLoad -- Page Unloading


21) How to debug javascript or vbscript in .Net?
For debugging the client side script enable the debugging in IE.a. Open Microsoft Internet Explorer.b. On the Tools menu click Internet Options.c. On the Advanced tab locate the Browsing section clear the Disable script debugging check box and then click OK.d. Close Internet Explorer.

22) How to validate xmlschema in xml document?
One can validate the XML document againest a given schema using the .Net class under the package System.Xml.Schema; like using XMLSchemaValidator and XmlSchema.

23) What is the maximum number of cookies that can be allowed to a web site

- A maximum of 300 cookies can be stored on the user's system.
- No cookie can be larger than 4 kilobytes.
- No server or domain can place more than 20 cookies on a user's system. (One website can't hog all 300 cookies.)
- If you go beyond the maximum the browser will just discard old cookies to make room for the new ones.

24) What do you mean by authentication and authorization?
Authentication is the process of validating a user on the credentials (username and password) and authorization performs after authentication. After Authentication a user will be verified for performing the various tasks, It access is limited it is known as authorization.

25) What you thing about the WebPortal ?
Answer: Web portal is nothing but a page that allows a user to customize his/her homepage. We can use Widgets to create that portal we have only to drag and drop widgets on the page. The user can set his Widgets on any where on the page where he has to get them. Widgets are nothing but a page area that helps particular function to response. Widgets example are address books, contact lists, RSS feeds, clocks, calendars, play lists, stock tickers, weather reports, traffic reports, dictionaries, games and another such beautiful things that we can not imagine. We can also say Web Parts in Share Point Portal. These are one of Ajax-Powered.

26) How to start Outlook,NotePad file in AsP.NET with code ?
Answer: Here is the syntax to open outlook or notepad file in ASP.NET VB.NET Process.Start("Notepad.exe") Process.Start("msimn.exe"); C#.NET System.Diagnostics.Process.Start("msimn.exe"); System.Diagnostics.Process.Start("Notepad.exe");

27) What is the purpose of IIS ?
Answer: We can call IIS(Internet Information Services) a powerful Web server that helps us creating highly reliable, scalable and manageable infrastructure for Web application which runs on Windows Server 2003. IIS helps development center and increase Web site and application availability while lowering system administration costs. It also runs on Windows NT/2000 platforms and also for above versions. With IIS, Microsoft includes a set of programs for building and administering Web sites, a search engine, and support for writing Web-based applications that access database. IIS also called http server since it process the http request and gets http response.

28) What is the difference between Trace and Debug?
Trace and Debug - There are two main classes that deal with tracing - Debug and Trace. They both work in a similar way - the difference is that tracing from the Debug class only works in builds that have the DEBUG symbol defined, whereas tracing from the Trace class only works in builds that have the TRACE symbol defined. Typically this means that you should use System.Diagnostics.Trace.WriteLine for tracing that you want to work in debug and release builds, and System.Diagnostics.Debug.WriteLine for tracing that you want to work only in debug builds.

29) What is @@connection?

The Query Designer supports the use of certain SQL Server constants, variables, and reserved column names in the Grid or SQL panes. Generally, you can enter these values by typing them in, but the Grid pane will not display them in drop-down lists. Examples of supported names include:
· IDENTITYCOL If you enter this name in the Grid or SQL pane, the SQL Server will recognize it as a reference to an auto-incrementing column.
· Predefined global values You can enter values such as @@CONNECTIONS and @@CURSOR_ROW into the Grid and SQL panes.
· Constants (niladic functions) You can enter constant values such as CURRENT_TIMESTAMP and CURRENT_USER in either pane.
· NULL If you enter NULL in the Grid or SQL panes, it is treated as a literal value, not a constant.

30) what is diff between varcher and nvarchar?

VARCHAR is an abbreviation for variable-length character string. It's a string of text characters that can be as large as the page size for the database table holding the column in question. The size for a table page is 8,196 bytes, and no one row in a table can be more than 8,060 characters. This in turn limits the maximum size of a VARCHAR to 8,000 bytes.
The "N" in NVARCHAR means uNicode. Essentially, NVARCHAR is nothing more than a VARCHAR that supports two-byte characters. The most common use for this sort of thing is to store character data that is a mixture of English and non-English symbols — in m UTF-8). That said, NVARCHAR strings have the same length restrictions as their VARCHAR cousins — 8,000 bytes. However, since NVARCHARs use two bytes for each character, that means a given NVARCHAR can only hold 4,000 characters (not bytes) maximum. So, the amount of storage needed for NVARCHAR entities is going to be twice whatever you'd allocate for a plain old VARCHAR.
Because of this, some people may not want to use NVARCHAR universally, and may want to fall back on VARCHAR — which takes up less space per row — whenever possible.
may case, English and Japanese.

31)What is the maximum size of the file that I can upload using file upload control?
Ans. 4MB

32) What class all aspx pages inherits?

Ans.
System.Web.UI.Page

33) What is NewID?
Yes, newid() is unique. newid() returns a globally unique identifier. newid() will be unique for each call of newid().
Thus, newid() can be used as the value of a primary key of a sql server table. Values returned by newid() can be inserted into a primary key column of type "uniqueidentifier". Here is an example of a "uniqueidentifier" primary key column, with newid() used as the default value:
CREATE TABLE [tblUsers] (
[UserId] [uniqueidentifier] NOT NULL DEFAULT (newid()),
[UserName] [varchar](256) NOT NULL,
PRIMARY KEY ([UserId])

34) What is the use of AutoWireup in asp.net?

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

35) how do you differentiate managed code and unmanaged code?

Managed code :Code that is executed by the CLR. Managed code provides information (i.e., metadata) to allow the CLR to locate methods encoded in assembly modules, store and retrieve security information, handle exceptions, and walk the program stack. Managed code can access both managed data and unmanaged data. Managed data—Memory that is allocated and released by the CLR using Garbage Collection. Managed data can only be accessed by managed code

Unmanaged Code:Unmanaged code is what you use to make before Visual Studio .NET 2002 was released. Visual Basic 6, Visual C++ , It is compiled directly to machine code that ran on the machine where you compiled it—and on other machines as long as they had the same chip, or nearly the same. It didn't get services such as security or memory management from an invisible runtime; it got them from the operating system. And importantly, it got them from the operating system explicitly, by asking for them, usually by calling an API provided in the Windows SDK. More recent unmanaged applications got operating system services through COM calls.



Managed Code is what Visual Basic .NET and C# compilers create. It compiles to Intermediate Language (IL) not to machine code that could run directly on your computer.Managed code runs in the Common Language Runtime.

Unmanaged code is what you use to make before Visual Studio .NET 2002 was released.It compiled directly to machine code that ran on the machine where you compiled it—and on other machines as long as they had the same chip or nearly the same.

-------

The code which is under control of CLR (Common Language Runtime) is called managed code.

The code which takes Operating System help while execution is called unmanaged code.

Sql Server Question Answer

What is RDBMS?
Relational Data Base Management Systems (RDBMS) are database management systems that maintain data records and indices in tables. Relationships may be created and maintained across and among the data and tables. In a relational database, relationships between data items are expressed by means of tables. Interdependencies among these tables are expressed by data values rather than by pointers. This allows a high degree of data independence. An RDBMS has the capability to recombine the data items from different files, providing powerful tools for data usage.

What is normalization?
Database normalization is a data design and organization process applied to data structures based on rules that help build relational databases. In relational database design, the process of organizing data to minimize redundancy. Normalization usually involves dividing a database into two or more tables and defining relationships between the tables. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationships.

What are different normalization forms?

1NF: Eliminate Repeating Groups
Make a separate table for each set of related attributes, and give each table a primary key. Each field contains at most one value from its attribute domain.
2NF: Eliminate Redundant Data
If an attribute depends on only part of a multi-valued key, remove it to a separate table.
3NF: Eliminate Columns Not Dependent On Key
If attributes do not contribute to a description of the key, remove them to a separate table. All attributes must be directly dependent on the primary key
BCNF: Boyce-Codd Normal Form
If there are non-trivial dependencies between candidate key attributes, separate them out into distinct tables.
4NF: Isolate Independent Multiple Relationships
No table may contain two or more 1:n or n:m relationships that are not directly related.
5NF: Isolate Semantically Related Multiple Relationships
There may be practical constrains on information that justify separating logically related many-to-many relationships.
ONF: Optimal Normal Form
A model limited to only simple (elemental) facts, as expressed in Object Role Model notation.
DKNF: Domain-Key Normal Form
A model free from all modification anomalies.

Remember, these normalization guidelines are cumulative. For a database to be in 3NF, it must first fulfill all the criteria of a 2NF and 1NF database.

What is Stored Procedure?
A stored procedure is a named group of SQL statements that have been previously created and stored in the server database. Stored procedures accept input parameters so that a single procedure can be used over the network by several clients using different input data. And when the procedure is modified, all clients automatically get the new version. Stored procedures reduce network traffic and improve performance. Stored procedures can be used to help ensure the integrity of the database.
e.g. sp_helpdb, sp_renamedb, sp_depends etc.

What is Trigger?
A trigger is a SQL procedure that initiates an action when an event (INSERT, DELETE or UPDATE) occurs. Triggers are stored in and managed by the DBMS.Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion. A trigger cannot be called or executed; the DBMS automatically fires the trigger as a result of a data modification to the associated table. Triggers can be viewed as similar to stored procedures in that both consist of procedural logic that is stored at the database level. Stored procedures, however, are not event-drive and are not attached to a specific table as triggers are. Stored procedures are explicitly executed by invoking a CALL to the procedure while triggers are implicitly executed. In addition, triggers can also execute stored procedures.
Nested Trigger: A trigger can also contain INSERT, UPDATE and DELETE logic within itself, so when the trigger is fired because of data modification it can also cause another data modification, thereby firing another trigger. A trigger that contains data modification logic within itself is called a nested trigger.

What is View?
A simple view can be thought of as a subset of a table. It can be used for retrieving data, as well as updating or deleting rows. Rows updated or deleted in the view are updated or deleted in the table the view was created with. It should also be noted that as data in the original table changes, so does data in the view, as views are the way to look at part of the original table. The results of using a view are not permanently stored in the database. The data accessed through a view is actually constructed using standard T-SQL select command and can come from one to many different base tables or even other views.

What is Index?
An index is a physical structure containing pointers to the data. Indices are created in an existing table to locate rows more quickly and efficiently. It is possible to create an index on one or more columns of a table, and each index is given a name. The users cannot see the indexes, they are just used to speed up queries. Effective indexes are one of the best ways to improve performance in a database application. A table scan happens when there is no index available to help a query. In a table scan SQL Server examines every row in the table to satisfy the query results. Table scans are sometimes unavoidable, but on large tables, scans have a terrific impact on performance.

Clustered indexes define the physical sorting of a database table’s rows in the storage media. For this reason, each database table may have only one clustered index.
Non-clustered indexes are created outside of the database table and contain a sorted list of references to the table itself.

Have you used cursors in sqlserver?
Ans.
Cursors can be considers as named result sets which allow a user to move through each record one by one. SQL Server 2000 provide different types of cursors to support different type of scrolling options.

When we use a Select statement in a stored procedure to get some result, we can get a collection of all the records which satisfy the given criteria. This result set can be returned back as a whole to the client application. We can’t move through each individual record one by one in this situation inside a stored procedure. Therefore, whenever we find some situation where we need to process each record individually we can use cursors.

In order to work with a cursor we need to perform some steps in the following order

1. Declare cursor
2. Open cursor
3. Fetch row from the cursor
4. Process fetched row
5. Close cursor
6. Deallocate cursor

DECLARE @name VARCHAR(50) -- database name
DECLARE @path VARCHAR(256) -- path for backup files
DECLARE @fileName VARCHAR(256) -- filename for backup
DECLARE @fileDate VARCHAR(20) -- used for file name

SET @path = 'C:\Backup\'

SELECT @fileDate = CONVERT(VARCHAR(20),GETDATE(),112)

DECLARE db_cursor CURSOR FOR
SELECT name
FROM master.dbo.sysdatabases
WHERE name NOT IN ('master','model','msdb','tempdb')

OPEN db_cursor
FETCH NEXT FROM db_cursor INTO @name

WHILE @@FETCH_STATUS = 0
BEGIN
SET @fileName = @path + @name + '_' + @fileDate + '.BAK'
BACKUP DATABASE @name TO DISK = @fileName

FETCH NEXT FROM db_cursor INTO @name
END

CLOSE db_cursor
DEALLOCATE db_cursor

Asp.Net Question Answer

What is the difference between Finalize() and Dispose()?

Dispose() is called by as an indication for an object to release any unmanaged resources it has held.
Finalize() is used for the same purpose as dispose however finalize doesn’t assure the garbage collection of an object.
Dispose() operates determinalistically due to which it is generally preferred

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What is the difference between XML Web Services using ASMX and .NET Remoting using SOAP?

XML Web services are more restricted than objects exposed over .NET Remoting.
XML Web services support open standards that target cross-platform use.
XML Web services are generally easier to create and due to the restricted nature of XML Web services, the design issues are simplified.
XML Web services support only SOAP message formatting, which uses larger XML text messages.
Communication with .NET Remoting can be faster than XML Web service communication with a binary formatter.
XML Web services are designed for use between companies and organizations.
XML Web services don't require a dedicated hosting program because they are always hosted by ASP.NET.
Consumers can use XML Web services just as easily as they can download HTML pages from the Internet. Thus there's no need for an administrator to open additional ports on a firewall as they work through MS-IIS and ASP.NET

______________
Explain how to add controls dynamically to the form using C#.NET.

The following code can be called on some event like page load or onload of some image or even a user action like onclick

protected void add_button(Button button)
{
try
{
panel1.Controls.Add(button); // Add the control to the container on a page
}
catch (Exception ex)
{
label1.Text += ex.Message.ToString();
}
}

______________
Why is an Object Pool required?

The request for the creation of an object is served by allocating an object from the pool.

This reduces the overhead of creating and re-creating objects each time an object creation is required.

C#.Net - Why is an object pool required?

To enhance performance and reduce the load of creating new objects, instead re using existing objects stored in memory pool. Object Pool is a container of objects that are for use and have already been created. Whenever an object creation request occurs, the pool manager serves the request by allocating an object from the pool. This minimizes the memory consumption and system's resources by recycling and re-using objects. When the task of an object is done, it is sent to the pool rather than being destroyed. This reduces the work for garbage collector and fewer memory allocations occur.

______________

What are ILDASM and Obfuscator in NET?

ILDASM (Intermediate Language Disassembler)
De-Compilation is the process of getting the source code from the assembly.
ILDASM is a de-compiler provided by Microsoft.
This ILDASM converts an assembly to instructions from which source code can be obtained.
Obfuscated code is source code or intermediate language that is very hard to read and understand.
An obfuscator is a medium of making a program difficult to understand.
The way the code runs remains unaffected although the obfuscator makes it harder to hack the code and hijack the program.
C#.Net - What is ILDASM and Obfuscator in NET?

ILDASM is MSIL Disassmbler. This take a portable executable (PE), which consists of MSIL code, and creates a text file which can then be used as an input for ILASM.exe, which is MSIL assembler. ILDASM can parse any .Net dll or exe and shows information in human readable form. It displays MSIL, namespaces, types and interfaces. It's normally used to examine assemblies and understand what the assembly is capable of.

Obfuscator is a tool to protect .Net assemblies and exe files. The tool renames all possible symbols, types, interfaces, namespaces etc into meaningless values and removes all unnecessary information. This reduces the size of the assemblies and also helps in protecting the code. It's normally used to protect the assemblies from exposing information for reverse engineering.

_____________

What is the GAC? What problem does it solve?

Global Assembly Cache (GAC):

Any system that has the CLR (common language runtime) installed, has a machine-wide code cache known as GAC.

Assemblies deployed in the global assembly cache need to have a strong name.

The Global Assembly Cache tool (Gacutil.exe), provided by the .NET Framework SDK can be used to deploy assemblies to GAC.
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