Hi,
Please give an example: which dns server is n/a from which provider? (i think it's an urban legend...)
I have seen this here in dresden with telekom and arcor dns servers. I used the dns server from telekom that we got while connecting via DSL. This is not working if the router that offers internet connection is connected to VDSL or Alice. I could use DNS server of acor for the router that was connected to the VDSL. But as you can not predict which gateway is used, you must habe a different solution. I therefore use a script that always set the dns server to the router ip that currently is used as gateway. The router ensures that dns is working.
/Stephan
--------------------------------------- Dipl.Informatiker(FH) Stephan Enderlein Freifunk Dresden