If you are trying to prevent dhcp from overwriting your DNS entries in /etc/resolv.conf on Redhat/Fedora, just add the following line to /etc/sysconfig/network-scripts/ifcfg-eth0 (or whatever dynamic interface you use):
new_domain_name_servers="192.168.1.1 192.168.1.2 192.168.1.3"
Or whatever nameservers you use. Just restart your network interface and the change will be applied.
