IP & DNS for net install

I always wonder why, when you do a network install (using inst-source on the net) we are first prompted for DNS IP then for server IP. if you have all ip's, why the DNS? and if the DNS works, why not a server name? thanks jdd -- http://www.dodin.net http://dodin.org/galerie_photo_web/expo/index.html http://lucien.dodin.net http://fr.susewiki.org/index.php?title=Gérer_ses_photos