ppoff probably means you are using
pppd. In which case
pon will execute the script
/etc/ppp/ppp_on_boot. Unless you supply an argument to
pon, it will load settings from
/etc/ppp/peers/provider. If you provide an argument it will say for example
pon interwebz it will look for
/etc/ppp/peers/interwebz. There is also
/etc/ppp/options to check too.
I would imagine that this file contains the setting
usepeerdns. From the pppd man page:
Ask the peer for up to 2 DNS server addresses. The addresses supplied by the peer
(if any) are passed to the /etc/ppp/ip-up script in the environment variables
DNS1 and DNS2, and the environment variable USEPEERDNS will be set to 1. In
addition, pppd will create an /etc/ppp/resolv.conf file containing one or two
nameserver lines with the address(es) supplied by the peer.
Comment out this option, stop
poff, edit your
resolv.conf and then restart your
pon and see if that resolves the issue.
If you edit your interface settings file (
/etc/sysconfig/network-scripts/ifcfg-eth0 for eth0), you can see what settings network manager is using.
If you have DHCP running on that interface
BOOTPROTO=yes then you can tell it not to override your DNS settings with
PEERDNS=no. If you are using a static address then you can set your DNS settings with