dns dhcp masquerade
 

I have been lookin' for a list of DNS servers assigned by my ISP, cached on my box for quite some time. /var/lib/dhcp contains a file called dhclient-INTERFACE.leases This file contains all the information you needed from your ISP. It gives default gateway, dns servers (3), your ip address, and the dhcp servers address. It's kinda like ipconfig /all in windows. Just less the file and have a look.

This info is from fedora core3 with kernel 2.6.11.12. I don't know if it applies for any of the other systems.

Useful info. You could also use http://www.dnsstuff.com/tools/aboutyou.ch to view DNS servers and browser info.