Interview Tips Interview Tips, Interview Questions and Answers

15Jul/100

Explain the ways of authentication techniques in ASP.NET

Selection of an authentication provider is done through the entries in the web.config file for an application.

The modes of authentication are:

<authentication mode=”windows”>
<authentication mode=”passport”>
<authentication mode=”forms”>

Custom authentication needs installation of ISAPI filter in IIS. It compares incoming requests to a list of source IP addresses and a request is considered to be authenticated if it comes from an acceptable address.

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12Jul/100

Describe how the ASP.NET authentication process works

ASP.NET runs inside the process of IIS due to which there are two authentication layers which exist in the system.

First authentication happens at the IIS level and the second at ASP.NET level per the WEB.CONFIG file.

Working:

At first, IIS ensures that the incoming request is from an authenticated IP address.
Otherwise the request is rejected.

By default IIS allows anonymous access due to which requests are automatically authenticated.

However, if this is changed, IIS performs its own user authentication too.

ASP.net checks if impersonation is enabled if a request is passed to ASP.net by an authenticated user. If it is enabled, ASP.net acts itself as an authenticated user else it acts with its own configured account.

Finally the OS resources are requested by the identity obtained from previous step.
The user is granted the resources if the authentication is successful else the resources are denied.

Resources can include ASP.net page, code access security features to extend authorization step to disk files, registry keys, etc.

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9Jul/100

Describe the basic schema of a .config file.

Configuration File Schema for the .NET Framework

Configuration Files are standard XML files.

The elements that implement configuration settings are:
<configuration> Element is the top-level element for all configuration files.
<assemblyBinding> Element specifies assembly binding policy at the configuration level.
<linkedConfiguration> Element specifies a configuration file to include.

The configuration schema is for the machine configuration file, application configuration files, and the security configuration file. The following schemas describe their element purposes:

  • Startup Settings Schema – specification of version of the CLR to be used.
  • Runtime Settings Schema – configuration of assembly binding and runtime behavior.
  • Network Settings Schema – specification of .NET connection to the Internet. \
  • Cryptography Settings Schema - mapping friendly algorithm names to classes that implement cryptography algorithms.
  • Configuration Sections Schema - creation and use of configuration sections for custom settings.
  • Trace and Debug Settings Schema – specification of trace switches and listeners.
  • Compiler and Language Provider Settings Schema – specification of compiler configuration for available language providers.
  • Application Settings Schema – enabling Windows Forms or ASP.NET applications to store and retrieve application-scoped and user-scoped settings.
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2Jul/100

Flash Control for ASP.NET

Features

Works with .NET framework 2.0, 3.0 and 3.5

FlashControl supports all Flash properties :

Width, Height, Src, FlashVars, PluginsPage, Loop, Menu, Scale, BgColor, SwLiveConnect, Quality, Play, Base, Align, SAlign, WMode, AllowScriptAccess, AllowNetworking, SeamlessTabbing, Devicefont.
Ready for ASP.NET AJAX!
FlashControl fully works with ASP.NET AJAX UpdatePanel.

Supports communication between Flash and JavaScript.

FlashControl works with ASP.NET 2.0 Theme service and Skin files !
Full Visual Studio 2005 and 2008 Designer support :

Smart Tag!
Custom Designer
Custom Editors
Custom template
Web Resources
FlashControl provide a XHTML compliance mode ! The rendered code validates XHTML 1.0 strict in compliance with W3C web standards.

With FlashControl you can target specific HTML output : Internet Explorer Windows ( tag) and/or Netscape/Mozilla, IE MAC ( tag) or use Automatic browser detection (FlashControl will automatically choose to render tag or tag depending on browser capabilities).

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12Jun/101

ASP.NET AJAX Interview Questions

The ASP.NET AJAX Interview Questions contains the most frequently asked questions in ASP.NET AJAX. These lists of questions will gauge your familiarity with the ASP.NET AJAX platform.
What is Ajax?
The term Ajax was coined by Jesse James Garrett and is a short form for "Asynchronous Javascript and XML". Ajax represents a set of commonly used techniques, like HTML/XHTML, CSS, Document Object Model(DOM), XML/XSLT, Javascript and the XMLHttpRequest object, to create RIA's (Rich Internet Applications).
Ajax gives the user, the ability to dynamically and asynchronously interact with a web server, without using a plug-in or without compromising on the user’s ability to interact with the page. This is possible due to an object found in browsers called the XMLHttpRequest object.
What is ASP.NET AJAX?
‘ASP.NET AJAX’ is a terminology coined by Microsoft for ‘their’ implementation of AJAX, which is a set of extensions to ASP.NET. These components allow you to build rich AJAX enabled web applications, which consists of both server side and client side libraries.
Which is the current version of ASP.NET AJAX Control Toolkit?
As of this writing, the toolkit version is Version 1.0.20229 (if you are targeting Framework 2.0, ASP.NET AJAX 1.0 and Visual Studio 2005) and Version 3.0.20229 (if targeting .NET Framework 3.5 and Visual Studio 2008).
What role does the ScriptManager play?
The ScriptManager manages all ASP.NET AJAX resources on a page and renders the links for the ASP.NET AJAX client libraries, which lets you use AJAX functionality like PageMethods, UpdatePanels etc. It creates the PageRequestManager and Application objects, which are prominent in raising events during the client life cycle of an ASP.NET AJAX Web page. It also helps you create proxies to call web services asynchronously.
Can we use multiple ScriptManager on a page?
No. You can use only one ScriptManager on a page.
What is the role of a ScriptManagerProxy?
A page can contain only one ScriptManager control. If you have a Master-Content page scenario in your application and the MasterPage contains a ScriptManager control, then you can use the ScriptManagerProxy control to add scripts to content pages.
Also, if you come across a scenario where only a few pages in your application need to register to a script or a web service, then its best to remove them from the ScriptManager control and add them to individual pages, by using the ScriptManagerProxy control. That is because if you added the scripts using the ScriptManager on the Master Page, then these items will be downloaded on each page that derives from the MasterPage, even if they are not needed, which would lead to a waste of resources.
What are the requirements to run ASP.NET AJAX applications on a server?
You would need to install ‘ASP.NET AJAX Extensions’ on your server. If you are using the ASP.NET AJAX Control toolkit, then you would also need to add the AjaxControlToolkit.dll in the /Bin folder.
Note: ASP.NET AJAX 1.0 was available as a separate downloadable add-on for ASP.NET 2.0. With ASP.NET 3.5, the AJAX components have been integrated into ASP.NET.
Explain the UpdatePanel?
The UpdatePanel enables you to add AJAX functionality to existing ASP.NET applications. It can be used to update content in a page by using Partial-page rendering. By using Partial-page rendering, you can refresh only a selected part of the page instead of refreshing the whole page with a postback.
Can I use ASP.NET AJAX with any other technology apart from ASP.NET?
To answer this question, check out this example of using ASP.NET AJAX with PHP, to demonstrate running ASP.NET AJAX outside of ASP.NET. Client-Side ASP.NET AJAX framework can be used with PHP and Coldfusion.
How can you cancel an Asynchronous postback?
Yes you can. Read my article over here.
Difference between Server-Side AJAX framework and Client-side AJAX framework?
ASP.NET AJAX contains both a server-side Ajax framework and a client-side Ajax framework. The server-side framework provides developers with an easy way to implement Ajax functionality, without having to possess much knowledge of JavaScript. The framework includes server controls and components and the drag and drop functionality. This framework is usually preferred when you need to quickly ajaxify an asp.net application. The disadvantage is that you still need a round trip to the server to perform a client-side action.
The Client-Side Framework allows you to build web applications with rich user-interactivity as that of a desktop application. It contains a set of JavaScript libraries, which is independent from ASP.NET. The library is getting rich in functionality with every new build released.
How can you debug ASP.NET AJAX applications?
Explain about two tools useful for debugging: Fiddler for IE and Firebug for Mozilla.
Can we call Server-Side code (C# or VB.NET code) from javascript?
Yes. You can do so using PageMethods in ASP.NET AJAX or using webservices.
Can you nest UpdatePanel within each other?
Yes, you can do that. You would want to nest update panels to basically have more control over the Page Refresh.
How can you to add JavaScript to a page when performing an asynchronous postback?
Use the ScriptManager class. This class contains several methods like the RegisterStartupScript(), RegisterClientScriptBlock(), RegisterClientScriptInclude(), RegisterArrayDeclaration(),RegisterClientScriptResource(), RegisterExpandoAttribute(), RegisterOnSubmitStatement() which helps to add javascript while performing an asynchronous postback.
Explain differences between the page execution lifecycle of an ASP.NET page and an ASP.NET AJAX page?
In an asynchronous model, all the server side events occur, as they do in a synchronous model. The Microsoft AJAX Library also raises client side events. However when the page is rendered, asynchronous postback renders only the contents of the update panel, where as in a synchronous postback, the entire page is recreated and sent back to the browser.
Explain the AJAX Client life-cycle events
Here’s a good article about the same.
Is the ASP.NET AJAX Control Toolkit(AjaxControlToolkit.dll) installed in the Global Assembly Cache?
No. You must copy the AjaxControlToolkit.dll assembly to the /Bin folder in your application.
Those were some frequently asked questions you should have knowledge about. In one of the coming articles, we will cover some more ASP.NET AJAX FAQ’s which were not covered in this article. I hope this article was useful and I thank you for viewing it.
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11Jun/100

What is a good C# ASP.NET MVC question to ask a prospective employee?

First things first. Do they even know what MVC. Not just the TAL but can they describe it to you. Then what are the benefits. Also it doesn't hurt to ask them their opinion on it. It is good to know if they even like MVC frameworks.

Next, ask them if they have used any other MVC frameworks. Struts, Spring MVC, Zend or anything like that.

Ask them if they know when a session starts, the general state problem on the net etc etc.

Also a little bit of database. Ask them if they have any experience with database persistence layers.

Then just because you can ask a hard technical question, ask them to write a function that compares two binary trees both in value and structure to see if they are identicial.

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9Jun/100

How does multi-threading work in .NET?

There are two main ways of multi-threading which .NET encourages:

To start your own threads with ThreadStart delegates, you should create a new thread "manually" for long-running tasks.

Using the ThreadPool class either directly (using ThreadPool.QueueUserWorkItem) or indirectly using asynchronous methods (such as Stream.BeginRead, or calling BeginInvoke on any delegate).

Use the thread pool only for brief jobs.

Benefits of using the Thread Pool.

Benefits of using the Thread Pool.

The benefits of using a Thread Pool are:

Thread creation and destruction overhead is negated,
Better performance and better system stability.
It is better to use a thread pool in cases where the number of threads is very large.

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