update documentation on CoreDNS

content/en/docs/concepts/services-networking/connect-applications-service.md

@@ -122,7 +122,7 @@ about the [service proxy](/docs/concepts/services-networking/service/#virtual-ip
 
 Kubernetes supports 2 primary modes of finding a Service - environment variables
 and DNS. The former works out of the box while the latter requires the
-[kube-dns cluster addon](http://releases.k8s.io/{{< param "githubbranch" >}}/cluster/addons/dns/kube-dns/README.md).
+[CoreDNS cluster addon](http://releases.k8s.io/{{< param "githubbranch" >}}/cluster/addons/dns/coredns).
 
 ### Environment Variables
 
@@ -178,7 +178,7 @@ kube-dns   ClusterIP   10.0.0.10    <none>        53/UDP,53/TCP   8m
 
 If it isn't running, you can [enable it](http://releases.k8s.io/{{< param "githubbranch" >}}/cluster/addons/dns/README.md#how-do-i-configure-it).
 The rest of this section will assume you have a Service with a long lived IP
-(my-nginx), and a DNS server that has assigned a name to that IP (the kube-dns
+(my-nginx), and a DNS server that has assigned a name to that IP (the CoreDNS
 cluster addon), so you can talk to the Service from any pod in your cluster using
 standard methods (e.g. gethostbyname). Let's run another curl application to test this:
 

content/en/docs/setup/independent/troubleshooting-kubeadm.md

@@ -258,6 +258,9 @@ kubectl -n kube-system get deployment coredns -o yaml | \
   kubectl apply -f -
 ```
 
+Another cause for CoreDNS to have `CrashLoopBackOff` is when a CoreDNS Pod deployed in Kubernetes detects a loop. [A number of workarounds](https://github.com/coredns/coredns/tree/master/plugin/loop#troubleshooting-loops-in-kubernetes-clusters)
+are available to avoid Kubernetes trying to restart the CoreDNS Pod every time CoreDNS detects the loop and exits.
+
 {{< warning >}}
 Disabling SELinux or setting `allowPrivilegeEscalation` to `true` can compromise
 the security of your cluster.

content/en/docs/setup/turnkey/gce.md

@@ -134,11 +134,11 @@ You'll see a list of pods that looks something like this (the name specifics wil
 
 ```shell
 NAMESPACE     NAME                                           READY     STATUS    RESTARTS   AGE
+kube-system   coredns-5f4fbb68df-mc8z8                       1/1       Running   0          15m
 kube-system   fluentd-cloud-logging-kubernetes-minion-63uo   1/1       Running   0          14m
 kube-system   fluentd-cloud-logging-kubernetes-minion-c1n9   1/1       Running   0          14m
 kube-system   fluentd-cloud-logging-kubernetes-minion-c4og   1/1       Running   0          14m
 kube-system   fluentd-cloud-logging-kubernetes-minion-ngua   1/1       Running   0          14m
-kube-system   kube-dns-v5-7ztia                              3/3       Running   0          15m
 kube-system   kube-ui-v1-curt1                               1/1       Running   0          15m
 kube-system   monitoring-heapster-v5-ex4u3                   1/1       Running   1          15m
 kube-system   monitoring-influx-grafana-v1-piled             2/2       Running   0          15m

content/en/docs/tasks/administer-cluster/coredns.md

@@ -63,6 +63,11 @@ value to `false`:
 kubeadm init --feature-gates=CoreDNS=false
 ```
 
+## Tuning CoreDNS
+
+When resource utilisation is a concern, it may be useful to tune the configuration of CoreDNS. For more details, check out the
+[documentation on scaling CoreDNS]((https://github.com/coredns/deployment/blob/master/kubernetes/Scaling_CoreDNS.md)).
+
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content/en/docs/tasks/administer-cluster/dns-custom-nameservers.md

@@ -103,7 +103,7 @@ The Corefile configuration includes the following [plugins](https://coredns.io/p
 * [proxy](https://coredns.io/plugins/proxy/): Any queries that are not within the cluster domain of Kubernetes will be forwarded to predefined resolvers (/etc/resolv.conf).
 * [cache](https://coredns.io/plugins/cache/): This enables a frontend cache.
 * [loop](https://coredns.io/plugins/loop/): Detects simple forwarding loops and halts the CoreDNS process if a loop is found.
-* [reload](https://coredns.io/plugins/reload): Allows automatic reload of a changed Corefile.
+* [reload](https://coredns.io/plugins/reload): Allows automatic reload of a changed Corefile. After editing the configuration in the ConfigMap, allow 2 mins for these changes to take effect in CoreDNS.
 * [loadbalance](https://coredns.io/plugins/loadbalance): This is a round-robin DNS loadbalancer by randomizing the order of A, AAAA, and MX records in the answer.
 
 We can modify the default behavior by modifying this configmap.
@@ -309,7 +309,7 @@ data:
 
 CoreDNS supports all the functionalities and more that is provided by kube-dns.
 A ConfigMap created for kube-dns to support `StubDomains`and `upstreamNameservers` translates to the `proxy` plugin in CoreDNS.
-Similarly, the `Federation` plugin translates to the `federation` plugin in CoreDNS.
+Similarly, the `Federations` plugin in kube-dns translates to the `federation` plugin in CoreDNS.
 
 ### Example