Just spit balling here, I had an issue like that as well. The issue I was running into was Network manager was applying it's configuration over Resolv.conf, might want to check that out. I am currently writhing this bored at work, I will get more specifics if needed once I get home.
grep DNS /etc/sysconfig/network-scripts/ifcfg-*
and see a DNS server in there and or
sudo vim /etc/NetworkManager/NetworkManager.conf
And add this to the [main] section:
dns=none
rc-manager=unmanaged