title: CIDR Address and advertise-address defining in Kubernetes Installation
body: <p>I am trying to install Kubernetes in my on-premise server Ubuntu 16.04. And referring following documentation ,</p>
  
  <p><a href="https://medium.com/@Grigorkh/install-kubernetes-on-ubuntu-1ac2ef522a36" rel="nofollow noreferrer">https://medium.com/@Grigorkh/install-kubernetes-on-ubuntu-1ac2ef522a36</a></p>
  
  <p>After installing kubelete kubeadm and kubernetes-cni I found that to initiate kubeadm with following command,</p>
  
  <pre><code>kubeadm init --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=10.133.15.28 --kubernetes-version stable-1.8
  </code></pre>
  
  <p>Here I am totally confused about why we are setting cidr and api server advertise address. I am adding few confusion from Kubernetes here,</p>
  
  <ol>
  <li>Why we are specifying CIDR and --apiserver-advertise-address here?</li>
  <li>How I can find these two address for my server?</li>
  <li>And why flannel is using in Kubernetes installation?</li>
  </ol>
  
  <p>I am new to this containerization and Kubernetes world.</p>