Kubernetes: Pods Can't Resolve Hostnames

Question

I am encountering an issue with Kubernetes where my pods cannot resolve hostnames (such as google.com or kubernetes.default).

I currently have

Answer 1

Encountered the same issue. I followed this doc dns-debugging-resolution and checked DNS related pods, services, endpoints, all was running without error messages. Finally, I found my calico service was dead. After I started calico service and waited several minutes, It worked.

Answer 2

I had a similar problem. Restarting the coredns deployment solved it for me:

kubectl -n kube-system rollout restart deployment coredns

Answer 3

Some ideas come to mind:

• Maybe the kube-proxy service is not working correctly and hence the kube-dns service is not acccessible. Could you check that it is working?
• You did not install a network overlay correctly, for example Calico: https://docs.projectcalico.org/v2.4/getting-started/kubernetes/installation/hosted/kubeadm/. Did you install it and it is working?

Answer 4

Check coredns pods log, if you see errors like:

# kubectl logs --namespace=kube-system coredns-XXX
  ...
  [ERROR] plugin/errors ... HINFO: read udp ... read: no route to host

Then make sure firewalld masquerade is enabled on the host:

# firewall-cmd --list-all
  ... 
  masquerade: yes

Enable if it's "no":
# firewall-cmd --add-masquerade --permanent
# firewall-cmd --reload

*You may need to restart/reboot after this