If you want to preserve /etc/resolv.conf configuration, following steps must be taken:

  1. include PEERDNS=no in your /etc/sysconfig/network-scripts/ifcfg-<your_interface>
  2. because initram rewrites ifcfg-* files every time system reboots (and we would loose our PEERDNS=no modification), initramfs must be modified to exclude ifcfg modules. Execute dracut -f -o ifcfg
  3. every new kernel image modifies initram, therefore it is necessary to force dracut not to modify it even new kernel is installed. Place 90-dracut.conf file to /etc/dracut.conf.d 
    omit_dracutmodules+="ifcfg"

Now you can modify your /etc/resolv.conf and test the changes by rebooting/restarting network.