ASP.Net Interview Questions 8

By | May 13, 2014

What is view state and use of it? The current property settings of an ASP.NET page and those of any ASP.NET server controls contained within the page. ASP.NET can detect when a form is requested for the first time versus when the form is posted (sent to the server), which  allows you to program accordingly.

What are user controls and custom controls? Custom controls:  A control authored by a user or a third-party software vendor that does not belong to   the .NET Framework class library. This is a generic term that includes user controls. A  custom server control is used in Web Forms (ASP.NET pages). A custom client control is used  in Windows Forms applications. User Controls: In ASP.NET: A user-authored server control that enables an ASP.NET page to be re-used   as a server control. An ASP.NET user control is authored declaratively  and persisted as a  text file with an .ascx extension. The ASP.NET page framework compiles a user control on  the fly to a class that derives from the        System.Web.UI.UserControl class.

What are the validation controls? A set of server controls included with ASP.NET that test user input in HTML and Web server  controls for programmer-defined requirements. Validation controls perform input checking in server code. If the user is working with a browser that supports DHTML, the validation  controls can also perform validation using client script.

What’s the difference between Response.Write() andResponse.Output.Write()? The latter one allows you to write formattedoutput.

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.

Where 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” and Src=”MyCode.aspx.cs”? CodeBehind is relevant to Visual Studio.NET only.

What’s a bubbled event? When you have a complex control, likeDataGrid, 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 over a certain button.

Where do you add an event handler? It’s the Attributesproperty, the Add function inside that property.             e.g. btnSubmit.Attributes.Add(“onMouseOver”,”someClientCode();”)

What data type does the RangeValidator control support? Integer,String and Date.

What are the different types of caching? Caching is a technique widely used in computing to increase performance by keeping frequently accessed or expensive data in memory. In context of web application, caching is used to retain the pages or data across HTTP requests and reuse them without the expense of recreating them.ASP.NET has 3 kinds of caching strategiesOutput CachingFragment CachingData     CachingOutput Caching: Caches the dynamic output generated by a request. Some times it is useful to cache  the output of a website even for a minute, which will result in a better  performance. For caching the whole page the page should have OutputCache directive.<%@ OutputCache Duration=”60″ VaryByParam=”state” %> Fragment Caching: Caches the portion of the  page generated by the request. Some times it is not practical to cache the entire page, in such cases we can cache a portion of page<%@ OutputCache Duration=”120″ VaryByParam=”CategoryID;SelectedID”%> Data Caching: Caches the objects programmatically. For     data caching provides a cache object for eg: cache[“States”] = dsStates;

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.

What are different types of directives in .NET? @Page: Defines page-specific attributes used by the ASP.NET page parser and compiler. Can       be included only in .aspx files <%@ Page AspCompat=”TRUE” language=”C#” %>   @Control:Defines control-specific attributes used by the ASP.NET page parser and        compiler. Can be included only in .ascx files. <%@ Control Language=”VB” EnableViewState=”false” %> @Import: Explicitly imports a namespace into a page or user control. The Import         directive cannot have more than one namespace attribute. To import multiple     namespaces,     use multiple @Import directives. <% @ Import Namespace=”System.web” %> @Implements: Indicates that the current page or user control implements the specified .NET      framework interface.<%@ Implements Interface=”System.Web.UI.IPostBackEventHandler” %> @Register: Associates aliases with namespaces and class names for concise notation in   custom server control syntax.<%@ Register Tagprefix=”Acme” Tagname=”AdRotator” Src=”AdRotator.ascx” %> @Assembly: Links an assembly to the current page during compilation, making all         the     assembly’s classes and interfaces available for use on the      page. <%@ Assembly Name=”MyAssembly” %><%@ Assembly Src=”MySource.vb” %> @OutputCache: Declaratively controls the output caching policies of an ASP.NET page or a        user control contained in a page<%@ OutputCache Duration=”#ofseconds” Location=”Any | Client | Downstream | Server | None” Shared=”True | False” VaryByControl=”controlname” VaryByCustom=”browser | customstring” VaryByHeader=”headers” VaryByParam=”parametername” %> @Reference: Declaratively indicates that another user control or page source file               should be dynamically compiled and linked against the page in which this directive is   declared.

How do I debug an ASP.NET application that wasn’t written with Visual Studio.NET and that doesn’t use code-behind? Start the DbgClr debugger that comes with the .NET Framework SDK, open the file containing      the code you want to debug, and set your breakpoints. Start the ASP.NET application. Go back to DbgClr, choose Debug Processes from the Tools menu, and select  aspnet_wp.exe from  the list of processes. (If aspnet_wp.exe doesn’t appear in the list,check the “Show system      processes” box.) Click the Attach button to attach to aspnet_wp.exe and begin debugging. Be sure to enable debugging in the ASPX file before debugging it with DbgClr. You can   enable tell ASP.NET to build debug executables by placing a <%@ Page Debug=”true” %>   statement at the top of an ASPX file or a   <COMPILATION debug=”true” />statement in a Web.config file.  

Can a user browsing my Web site read my Web.config or Global.asax files? No. The <HTTPHANDLERS>section of Machine.config, which holds the master configuration  settings for ASP.NET, contains entries that map ASAX files, CONFIG files, and selected  other file types to an HTTP handler named HttpForbiddenHandler, which fails attempts to retrieve the associated file. You can modify it by editing  Machine.config or including an section in a local Web.config file.

What’s the difference between Page.RegisterClientScriptBlock and Page.RegisterStartupScript? RegisterClientScriptBlock is for returning blocks of client-side script containing functions. RegisterStartupScript is for returning blocks of client-script not   packaged in functions-in other words, code that’s to execute when the page is loaded. The latter positions script blocks near the end of the document so elements on the page that the script interacts are loaded before the script runs.<%@ Reference Control=”MyControl.ascx” %>

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