k8s下有一个核心组件是coredns
=> kubectl get all -n kube-system -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
...
pod/coredns-86966648-crrt5 1/1 Running 9 (4d12h ago) 4d18h 192.168.235.195 k8s-master <none