<p>I ping kubernetes pod ip from host,it success. So what is the procedure about it?  I read many to talk pod to pod communication,but nothing about host to pod. According my knownlege, The kubernetes cluster is individual about host machine and communication through edge nodes ingress controller.I am confusing about this.</p>

Dolphin
<p>In fact this is Docker's behaviour, not Kubernetes <em>(supposing you're using Docker as your container runtime)</em>.</p>

<p>By default, when you install Docker, there is a default network interface that is created on your host : <strong>docker0</strong> (you should be able to see it with <code>ifconfig</code>). This interface is an ethernet bridge device.<br>
So as stated in the documentation :</p>

<blockquote>
  <p>If you don’t specify a different network when starting a container, the container is connected to the bridge and all traffic coming from and going to the container flows over the bridge to the Docker daemon, which handles routing on behalf of the container.</p>
</blockquote>

<p>This is why you can ping your container from your host.</p>

<p>If you want to customize default IP range for this interface, you can refer to the <a href="https://docs.docker.com/v17.09/engine/userguide/networking/default_network/custom-docker0/" rel="nofollow noreferrer">official documentation</a></p>
