Apply validation to dropdownlist

Question

Hi

Can i attach a RequiredFieldValidator to dropdownlist in asp.net2.0?
i want to make it mandatory for the user to select an option from the
dropdownlist.
i can validate it by writing code in my code-behind file, but can i have the
dropdown validated at the client side only? Just like we validate a textbox by a requiredfieldvalidator
on client side.