dhclient overwrites reslov.conf

[[LoN]Kamikaze]

I'm in a LAN with a relatively short lease time. That wouldn't be a problem if I wouldn't run a vpnc connection through this LAN. The vpnc connection sets /etc/resolv.conf as required, but dhclient overwrites it every couple of minutes, causing DNS not to work any more. Is there a way to make dhclient set up resolv.conf only when the IP of the interface is changed?