$ kubectl logs -n kube-system po/kube-dns-5d6f4dbccf-gt5j2
Error from server (BadRequest): a container name must be specified for pod kube-dns-5d6f4dbccf-gt5j2, choose one of: [kubedns dnsmasq sidecar]

root@k8s-server01:~/source/dns# kubectl logs -n kube-system po/kube-dns-5d6f4dbccf-gt5j2 -c kubedns
I1101 01:49:49.294664       1 dns.go:48] version: 1.14.10
F1101 01:49:49.364594       1 server.go:56] Failed to create a kubernetes client: open /var/run/secrets/kubernetes.io/serviceaccount/token: no such file or directory