aks coredns quick debugging to see if the dns is working as expected

Use this yaml

apiVersion: v1

kind: Pod

metadata:

  name: dnsutils

  namespace: default

spec:

  containers:

  - name: dnsutils

    image: registry.k8s.io/e2e-test-images/jessie-dnsutils:1.3

    command:

      - sleep

      - "infinity"

    imagePullPolicy: IfNotPresent

  restartPolicy: Always

 Next you can start to 

Check default dns server

kubectl exec -i -t dnsutils -- nslookup kubernetes.default

Check /etc/resolv.conf file 

kubectl exec -ti dnsutils -- cat /etc/resolv.conf

It should look like this:-

search default.svc.cluster.local svc.cluster.local cluster.local google.internal c.gce_project_id.internal

nameserver 10.0.0.10

options ndots:5

Other steps to confirm 

Is the coredns pods running? 

kubectl get pods --namespace=kube-system -l k8s-app=kube-dns

Is the service up? 

kubectl get svc --namespace=kube-system

Is the endpoint exposed? 

kubectl get endpoints kube-dns --namespace=kube-system

Check corends pods for logs

kubectl logs --namespace=kube-system -l k8s-app=kube-dns