who/where actually work liveness probe in kubernetes?

kubernetes ubuntu-18.04 kubernetes-cluster

Did you check the DNS already ? using the busybox:1.28 try to execute dns lookup to the pod and see what you get.

nslookup pod-ip-in-dash.pod.cluster.local

Another thing you can do which you might already did, check in kube-system if coredns pod is running.

Let me know how went,

CodeHunter