nslookup kubernetes.default is stuck whereas nslookup kubernetes works fine

[msavlani]

Hi,

I am facing weird issues Kubernetes 1.5.2

Its a single 2 nodes cluster which is setup using "https://kubernetes.io/docs/getting-started-guides/centos/centos_manual_config/"

then i created skydns pods.

[root@masterhost ~]# kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
kube-dns-v20-jm7x7 3/3 Running 0 2h
kubernetes-dashboard-255567031-7dn4l 1/1 Running 44 11d

[root@mwhlvatd2d2 ~]# kubectl get services -n kube-system
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns 10.254.0.10 53/UDP,53/TCP 2h
kubelet None 10250/TCP 8d
kubernetes-dashboard 10.254.25.228 80:31000/TCP 24d

I created one busybox pod and tried to do nslookup for kubernetes service as follows

It worked fine.
[root@masterhost ~]# kubectl exec -ti busybox1 -- nslookup kubernetes
Server: 10.254.0.10
Address 1: 10.254.0.10 kube-dns.kube-system.svc.cluster.local

Name: kubernetes
Address 1: 10.254.0.1 kubernetes.default.svc.cluster.local

Then i did nslookup for kubernetes.default
[root@masterhost ~]# kubectl exec -ti busybox1 -- nslookup kubernetes.default
Server: 10.254.0.10
Address 1: 10.254.0.10 kube-dns.kube-system.svc.cluster.local

---- Here it got stuck for some time and then returned following error ;

nslookup: can't resolve 'kubernetes.default'

Expected result

[root@masterhost ~]# kubectl exec -ti busybox1 -- nslookup kubernetes.default.svc.cluster.local
Server: 10.254.0.10
Address 1: 10.254.0.10 kube-dns.kube-system.svc.cluster.local

Name: kubernetes.default.svc.cluster.local
Address 1: 10.254.0.1 kubernetes.default.svc.cluster.local

Any help here is appreciated.

[MrHohn]

Could you post the content of /etc/resolv.conf on that busybox? It would be even better if you can use dig to track the DNS querying sequence.

[bowei]

Please reopen and post updates if this is still an issue.