preferring the DNS server of one interface over another

[Laine Stump <laine laine org>]

I have a laptop (currently running Fedora 13, with 
NetworkManager-0.8.4-1.fc13.x86_64) that I sometimes use with a single 
ethernet, sometimes with that ethernet + a VPN connection, and sometimes 
plug in a 2nd ethernet onto a physical private network that provides the 
same connectivity as the VPN. When the 2nd ethernet is plugged in, 
sometimes its configured DNS servers are listed first in 
/etc/resolv.conf, and sometimes the others are (and it can periodically 
change, I'm assuming this happens when the DHCP lease is refreshed on 
one interface or the other).

To avoid disruptions in service, I need to be able to force the DNS 
server on the 2nd ethernet to always takes precedence over the DNS 
server on the 1st ethernet (ie, that it be listed first in resolv.conf), 
but I haven't found a way to specify that. Am I missing something, or 
does this functionality not exist?