/etc/resolv.conf reverts upon reboot: NetworkManager

Symptoms

After reboot, the contents of /etc/resolv.conf have changed or reverted to an old configuration.

Cause

NetworkManager can also control this behavior, and may need to be modified to prevent future recurrence.

Resolution

1. Modify the NetworkManager configuration:

   # /etc/NetworkManager/NetworkManager.conf

2. Locate the [main] section in that file, and add the following under it:

   # dns=none
   rc-manager=unmanaged

3. Save the file, and the resolv.conf changes should persist after reboots going forward.