thanks joe - on centos7 i added the following lines to /etc/sysconfig/network-scripts/ifcfg-eth0 as per https://www.cyberciti.biz/faq/dhclient-etcresolvconf-hooks/
PEERDNS=“yes” ## this was actually here already, added the two below:
DNS1=8.8.8.8
DNS2=127.0.0.1
that seemed to take care of it.