System.Web.Mail is not supported under version 3.5 of the Framework
System.Web.Mail is deprecated under version 3.5 of the Framework, and it is officially recommended that System.Net.Mail be used.
System.Web.Mail is the preferred solution when using IIS hosted applications.
There are no functional differences; the items were moved to a new namespace to better reflect their applicability
By default, Client side validation are defined in a script library called WebUIValidation.js. Useful resources, ASP.NET Validation
All of them
Useful resources, Tags for Documentation Comments
Setting the ToolTip property of a control to a string containing the information.
using the open method of the browser window object to open a new browser window and display a help related ASP.NET page.
Using the showHelp method of the browser window object to display a topic from a compiled help file (.chm).
All of the above
Styles can be applied to all elements having the same CSS Class attribute.
Styles can be applied to specific elements based on their ID attribute.
Styles can be applied to elements based on their position in a hierarchy.
Styles can be used to invoke script based code.
All of the above.
Useful resources, CSS Overview
It is optimized for single processor/core operations.
A thread which has a read lock on a resource may not acquire a write lock on the same resource.
By default, a thread which has a read lock on a resource and attempts to get another read lock on the same resource will throw an exception
Useful resources, ReaderWriterLockSlim Class
A specific number of requests to the application process.
A percentage of physical memory utilized by the process.
A specific time interval.
A specific date and time.
All of the above
Useful resources, Recycling Application Pool Settings
It must contain a from clause.
It must begin with a select clause.
It can end with a group clause
A query expression is a query expressed in query syntax. A query expression is a first-class language construct. It is just like any other expression and can be used in any context in which a C# expression is valid. A query expression consists of a set of clauses written in a declarative syntax similar to SQL or XQuery. Each clause in turn contains one or more C# expressions, and these expressions may themselves be either a query expression or contain a query expression.
Only the UpdatePanel and any child controls go through the server lifecycle.
The entire page always goes through the entire lifecycle.
Only the UpdatePanel which initiated the Postback and its child controls can provide updated information.
UpdatePanels can not be used with Master Pages.
TreeView,Menu,Substitution and Validatio controlscan not be used within and UpdatePanel
Useful resources, UpdatePane