There is Cancel button and OK button on page. When we click Cancel button it skips all validation controls and goes to next page.
(a)Page AutoPostback of Cancel is True. (b)Page AutoPostback of Cancel is False. (c)Page AutoPostback of OK is True. (d)Page AutoPostback of OK is False.
AutoPostBAck is a property of TextBox Control and not a button which is rendered as a summit and will submit the page. If the real question is about validation the cancel button normally has its property CauseValidation to false to enable the user to exit from a form without fulfilling the normal content of the form.
A button control does not have AutoPostBack property it has click event. so once you click on cancel and if its CausesValidation Property is false it will skips all validations and if it is true it will validate the controls on the page.
AutoPostBack property is for say DropDown textbox etc... whnever you change/enter value/keyed some caharcter in textbox or change your selection in drop down postback will happen if that control's is AutoPostBack property is true depending on that postback you can fill values or set some values for other controls or you can do some validation against enterd or selcted values.
e.g. say tehre are 2 drop down. DropDown1 and DropDown2 DropDown2 is currently holding states of US country as in DropDown1 you have selcted US. Now you want to fill DropDown2 with state value of India. Now if DropDown1.AutopostBack True;
and you change DropDown1's value from Us to India. Page will post back to server and you can fill DropDown2 with Indian States.
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