/etc/resolv.conf
will work to configure name resolution, but might not be persistent. This is the old way of doing things and assumes your host does not have NetworkManager running. NetworkManager will attempt to manage these files for you, and if you edit them by hand you can find them overwritten. This is likely what happened since the symptom appeared after reboot./etc/resolv.conf
suggests and configure your name servers in /etc/sysconfig/network-scripts/ifcfg-eth0
(Usually eth0...)