Restore firewalld.service file contents. [root@idmipa01 ~]# systemctl enable firewalld Failed to execute operation: Operation not supported [root@idmipa01 ~]#  [root@idmipa01 ~]# systemctl enable firewall Failed to execute operation: Access denied [root@idmipa01 ~]#  [root@idmipa01 system]# vi firewalld.service [root@idmipa01 system]# systemctl enable firewalld Created symlink from /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service to /usr/lib/systemd/system/firewalld.service. Created symlink from /etc/systemd/system/basic.target.wants/firewalld.service to /usr/lib/systemd/system/firewalld.service. [root@idmipa01 system]# systemctl […]

So /etc/resolv.conf was getting consistently overwritten even though NetworkManager was removed using rpm -e $(rpm -aq|grep Network Manager).  To find the culprit, we checked what is running on this CentOS 7 system using:

Setting Temporary Network Addresses ip a add 192.168.0.200/255.255.255.0 dev eth0 ip route add default 192.168.0.1/255.255.255.0 dev eth0 Cheers, TK