I have a Lenovo X200 laptop on which I am running Ubuntu 9.10. Recently, (I assume after some updating, but I really don't know) my ethernet port stopped working under Linux. A more tech/linux-savvy friend of mine was able to temporarily fix the problem by manually editing the resolv.conf file with the DNS servers he found through his connection. However, after rebooting, the problem came back and now I am looking for a more permanent solution.
you need to edit:
and prepend the dns severs to this. I think there is a commented out line for what you need.
resolv.conf is generated each time you boot.
actually resolv.conf is updated via ubuntu network manager upon getting a new lease from dhcp. your dhcp server ideally should give you a set of two nameservers to use in the local network. if you're behind a private broadband router it's likely that you accidentally disabled this dns feature there.
if you use the abovementioned dhclient.conf it is quite possible that your nameserver setting won't work as soon as you put your laptop in another network as not all recursive nameservers respond to all internet network ranges.