ASP.NET
Interview Questions
This
is a list of questions I have gathered and created over a period of
time from my experience, many of which I felt where incomplete
or simply wrong. I have finally taken the time to go through
each question and correct them to the best of my ability.
However, please feel free to post feedback to challenge, improve, or
suggest new questions. I want to thank those of you that have
contributed quality questions and corrections thus far.
There
are some questions in this list that I do not consider to be good
questions for an interview. However, they do exist on other
lists available on the Internet so I felt compelled to keep them here
for easy access.
Describe
the role of inetinfo.exe, aspnet_isapi.dll andaspnet_wp.exe
in the page loading process.
inetinfo.exe is theMicrosoft IIS
server running, handling ASP.NET requests among other things.When an
ASP.NET request is received (usually a file with .aspx extension),
the ISAPI filter aspnet_isapi.dll takes care of it by passing the
request tothe actual worker process aspnet_wp.exe.
What’s
the difference between Response.Write()
andResponse.Output.Write()?
Response.Output.Write() allows
you to write formatted output.
What
methods are fired during the page load?
Init() - when the
page is instantiated
Load() - when the page is loaded into server
memory
PreRender() - the brief moment before the page is
displayed to the user as HTML
Unload() - when page finishes
loading.
When
during the page processing cycle is ViewState available?
After
the Init() and before the Page_Load(), or OnLoad() for a control.
What
namespace does the Web page belong in the .NET Framework class
hierarchy?
System.Web.UI.Page
Where
do you store the information about the user’s
locale?
System.Web.UI.Page.Culture
What’s
the difference between Codebehind="MyCode.aspx.cs"
andSrc="MyCode.aspx.cs"?
CodeBehind is relevant to
Visual Studio.NET only.
What’s
a bubbled event?
When you have a complex control, like
DataGrid, writing an event processing routine for each object (cell,
button, row, etc.) is quite tedious. The controls can bubble up
their eventhandlers, allowing the main DataGrid event handler to
take care of its constituents.
Suppose
you want a certain ASP.NET function executed on MouseOver for
a certain button. Where do you add an event handler?
Add
an OnMouseOver attribute to the button. Example:
btnSubmit.Attributes.Add("onmouseover","someClientCodeHere();");
What
data types do the RangeValidator control support?
Integer,
String, and Date.
Explain
the differences between Server-side and Client-side
code?
Server-side code executes on the server.
Client-side code executes in the client's browser.
What
type of code (server or client) is found in a Code-Behind class?
The
answer is server-side code since code-behind is executed on the
server. However, during the code-behind's execution on the
server, it can render client-side code such as JavaScript
to be processed in the clients browser. But just to
be clear, code-behind executes on the server, thus making it
server-side code.
Should
user input data validation occur server-side or client-side?
Why?
All user input data validation should occur on the
server at a minimum. Additionally, client-side validation can
be performed where deemed appropriate and feasable to provide a
richer, more responsive experience for the user.
What
is the difference between Server.Transfer and Response.Redirect?
Why would I choose one over the other?
Server.Transfer
transfers page processing from one page directly to the
next page without making a round-trip back to the client's browser.
This provides a faster response with a little less overhead on the
server. Server.Transfer does not update the clients url
history list or current url. Response.Redirect is used to
redirect the user's browser to another page or site. This
performas a trip back to the client where the client's browser is
redirected to the new page. The user's browser history list is
updated to reflect the new address.
Can
you explain the difference between an ADO.NET Dataset and an ADO
Recordset?
Valid answers are:
· A DataSet can
represent an entire relational database in memory, complete with
tables, relations, and views.
· A DataSet is
designed to work without any continuing connection to the original
data source.
· Data in a DataSet is bulk-loaded,
rather than being loaded on demand.
· There's no
concept of cursor types in a DataSet.
· DataSets
have no current record pointer You can use For Each loops to move
through the data.
· You can store many edits in a
DataSet, and write them to the original data source in a single
operation.
· Though the DataSet is universal, other
objects in ADO.NET come in different versions for different data
sources.
What
is the Global.asax used for?
The
Global.asax (including the Global.asax.cs file) is used to implement
application and session level events.
What are
the Application_Start and Session_Start subroutines used for?
This
is where you can set the specific variables for the Application and
Session objects.
Can
you explain what inheritance is and an example of when you might use
it?
When you want to inherit (use the functionality of)
another class. Example: With a base class named Employee,
a Manager class could be derived from the Employee base class.
Whats
an assembly?
Assemblies are the building blocks of the .NET
framework.
Overview of assemblies from MSDN
Describe
the difference between inline and code behind.
Inline code
written along side the html in a page. Code-behind is code written
in a separate file and referenced by the .aspx page.
Explain
what a diffgram is, and a good use for one?
The DiffGram is
one of the two XML formats that you can use to render DataSet object
contents to XML. A good use is reading database data to
an XML file to be sent to a Web Service.
Whats
MSIL, and why should my developers need an appreciation of it if at
all?
MSIL is the Microsoft Intermediate Language. All .NET
compatible languages will get converted to MSIL. MSIL also
allows the .NET Framework to JIT compile the assembly on the
installed computer.
Which
method do you invoke on the DataAdapter control to load your
generated dataset with data?
The Fill() method.
Can
you edit data in the Repeater control?
No, it just reads the
information from its data source.
Which
template must you provide, in order to display data in a Repeater
control?
ItemTemplate.
How
can you provide an alternating color scheme in a Repeater
control?
Use the AlternatingItemTemplate.
What
property must you set, and what method must you call in your code,
in order to bind the data from a data source to the Repeater
control?
You must set the DataSource property and call the
DataBind method.
What
base class do all Web Forms inherit from?
The Page class.
Name
two properties common in every validation control?
ControlToValidate
property and Text property.
Which
property on a Combo Box do you set with a column name, prior to
setting the DataSource, to display data in the combo
box?
DataTextField property.
Which
control would you use if you needed to make sure the values in two
different controls matched?
CompareValidator control.
How
many classes can a single .NET DLL contain?
It can contain
many classes.
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