ok more thinking...
smart and yum are trying to call AAAA apt.sw.be and then AAAA apt.sw.be.localdomain and those fail. then it is turn to try A apt.sw.be and congratulation that works...so can someone tell me what is that AAAA I have searched net, could it be something to do with ipv6? when I'm surfing on the net I don't see that AAAA page because I turned those ipv6 things off...(thanks Seve)
but why this new adsl modem(RR24) is not working like old one (telewell ae400)