A reboot wiped the content of /etc/resolv.conf after configuring dns=none in NetworkManager.conf

Environment

• Red Hat Enterprise Linux (RHEL) 7
• Red Hat Enterprise Linux (RHEL) 8
• NetworkManager

Issue

• On a RHEL 7 and RHEL 8 server using NetworkManager, configuring the directive dns=none in /etc/NetworkManager/NetworkManager.conf and immediately rebooting the server results in a wipe of the pre-existing content of /etc/resolv.conf.

Resolution

• Restart the NetworkManager service before rebooting the server:

  # systemctl restart NetworkManager.service
  

Root Cause

• Without a restart of the NetworkManager service the directive dns=none is still not in use in the loaded configuration.
• NetworkManager will update the content of /etc/resolv.conf as part of its default behavior during the shutdown procedure.

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