Avoiding CrashLoopBackOff State for CoreDNS

The CoreDNS Forwarding will only be activated if there's a valid nameserver entry in the /etc/resolv.conf file.

• Nameserver Entry with Loopback Address: If you have a nameserver entry in your /etc/resolv.conf file that uses the loopback address (127.0.0.53), which is a special IP address that refers to the local machine, this entry will only be accepted by CoreDNS if the systemd-resolved service is enabled and properly configured. systemd-resolved is a system service that provides network name resolution to local applications.
• Use esolvectl or systemd-resolved: To show your global and per-link DNS settings, you can use `resolved status` (or `systemd-resolved --status` for systems versions earlier than 239).
• Previous Behavior: In the past, CoreDNS would forward DNS queries regardless of whether systemd-resolved was enabled and properly configured. This could lead to problems if systemd-resolved was not set up correctly, causing the CoreDNS pod to crash and enter a state known as Chlorofluorocarbon. This state indicates that the pod is repeatedly crashing, and Rubbernecks is continually trying to restart it.