title: What does --virtualbox-hostonly-cidr do during docker machine creation?
body: <p>Hi I want to create a Docker machine on Windows and have Docker Toolbox and have to execute this code</p>
  
  <pre><code>./docker-machine create -d virtualbox  --virtualbox-boot2docker-url https://github.com/boot2docker/boot2docker/releases/download/v1.11.2/boot2docker.iso --virtualbox-memory 3240 --virtualbox-cpu-count 2 --virtualbox-disk-size 30480 --virtualbox-hostonly-cidr "192.168.56.1/24" local
  </code></pre>
  
  <p>So I am wondering what is --virtualbox-hostonly-cidr  and does it make </p>
  
  <p>The official documentation says:</p>
  
  <pre><code>--virtualbox-hostonly-cidr "192.168.99.1/24"                                                         Specify the Host Only CIDR [$VIRTUALBOX_HOSTONLY_CIDR]
  </code></pre>
  
  <p>which I do not understand. Please can you explain in more details for a developer with low network culture.</p>