Can't resolve 'kubernetes' by skydns serivce in Kubernetes - kubernetes

Question

core#core-1-94 ~ $ kubectl exec -it busybox -- nslookup kubernetes
Server: 10.100.0.10
Address 1: 10.100.0.10
nslookup: can't resolve 'kubernetes'
core#core-1-94 ~ $ kubectl get svc --namespace=kube-system
NAME LABELS SELECTOR IP(S) PORT(S)
kube-dns k8s-app=kube-dns,kubernetes.io/cluster-service=true,kubernetes.io/name=KubeDNS k8s-app=kube-dns 10.100.0.10 53/UDP
53/TCP
kube-ui k8s-app=kube-ui,kubernetes.io/cluster-service=true,kubernetes.io/name=KubeUI k8s-app=kube-ui 10.100.110.236 80/TCP
core#core-1-94 ~ $ kubectl exec -it busybox -- nslookup kubernetes 10.100.0.10:53
Server: 10.100.0.10
Address 1: 10.100.0.10
nslookup: can't resolve 'kubernetes'
core#core-1-94 ~ $ kubectl get endpoints --namespace=kube-system
NAME ENDPOINTS
kube-dns 10.244.31.16:53,10.244.31.16:53
kube-ui 10.244.3.2:8080
core#core-1-94 ~ $ kubectl exec -it busybox -- nslookup kubernetes 10.244.31.16:53
Server: 10.244.31.16
Address 1: 10.244.31.16
Name: kubernetes
Address 1: 10.100.0.1
I think the service of kube-dns is Not available.
the skydns-svc.yaml :
apiVersion: v1
kind: Service
metadata:
name: kube-dns
namespace: kube-system
labels:
k8s-app: kube-dns
kubernetes.io/cluster-service: "true"
kubernetes.io/name: "KubeDNS"
spec:
selector:
k8s-app: kube-dns
clusterIP: 10.100.0.10
ports:
- name: dns
port: 53
protocol: UDP
- name: dns-tcp
port: 53
protocol: TCP
Who can help ?

Answer 1

For DNS to work, the kubelet needs to be passed the flags --cluster_dns= and --cluster_domain=cluster.local at startup. This flag isn't included in the set of flags passed to the kubelet, so the kubelet won't try to contact the DNS pod that you've created for name resolution services. To fix this, you can modify the script to add these two flags to the kubelet and then when you create a DNS service, you need to make sure that you set the same ip address that you passed to the --cluster_dns flag as the portalIP field of the service spec like this.
For any other information, you can look it.