Peeg, those are not appropriate commands. I would suggest "man resolv.conf".
Homik, You put dns servers in /etc/resolv.conf in similar lines:
nameserver 1.2.3.4
However, You can use GUI to do it as well. In Mandriva 2006 click (STAR)->System->Configuration->Configure Your Computer. You need root password to access the application. Then click "Network & Internet", then "Alter miscellaneous internet settings".
Easy like in Windows. Why people still think, that they need to use console all the time

?