I've been messing around with Kubernetes and have a small lab cluster of centos hosts (3 nodes, 1 master) running.

$ kubectl get nodes
NAME                           STATUS    AGE
centos-kube-minion-1   Ready     2d
centos-kube-minion-2   Ready     2d
centos-kube-minion-3   Ready     2d

I've manged to follow the interactive tutorial in my lab env (http://kubernetes.io/docs/tutorials/kubernetes-basics/expose-interactive/).

I've arrived at the part where you expose the demo app externally (Module 4 Step 1 of 3):

$ kubectl expose deployment/kubernetes-bootcamp --type="NodePort" --port 8080

Kubectl describe outputs as follows:

$ kubectl describe services/kubernetes-bootcamp
Name:                   kubernetes-bootcamp
Namespace:              default
Labels:                 run=kubernetes-bootcamp
Selector:               run=kubernetes-bootcamp
Type:                   NodePort
IP:                     10.254.224.254
Port:                   <unset> 8080/TCP
NodePort:               <unset> 31686/TCP
Endpoints:              172.30.3.2:8080
Session Affinity:       None
No events.

The next step in the tutorial calls for a curl on the node dns name(or IP) where the pod is running, and the exposed port (31686 in my case).

My /etc/hosts looks like this:

$ cat etc/hosts
...
10.10.0.231 centos-kube-master
10.10.0.236 centos-kube-minion-1
10.10.0.232 centos-kube-minion-2
10.10.0.237 centos-kube-minion-3

And the actual pod is running on minion-3:

   $ kubectl describe pod kubernetes-bootcamp-428840972-ukl15
    Name:           kubernetes-bootcamp-428840972-ukl15
    Namespace:      default
    Node:           centos-kube-minion-3/10.10.0.237

Yet, (and here's the actual question), when I curl any of those DNS entries and the exposed port, I hit the app:

$ curl centos-kube-minion-1:31686
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-428840972-ukl15 | v=1

$ curl centos-kube-minion-2:31686
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-428840972-ukl15 | v=1

$ curl centos-kube-minion-3:31686
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-428840972-ukl15 | v=1

I also curled against the actual IP to make sure nothing crazy was happening with the DNS entries.

$ curl 10.10.0.236:31686
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-428840972-ukl15 | v=1
$ curl 10.10.0.237:31686
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-428840972-ukl15 | v=1
$ curl 10.10.0.232:31686
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-428840972-ukl15 | v=1

So my question is: is this working as intended (I suspect yes)? (If so, can anyone explain/link to an explanation of the magic?)