title: vagrant box download cache and unzip
body: <p>So I am trying to download a box that is in a .zip format like so:</p>
  
  <pre><code>vagrant box add win7-ie10 http://aka.ms/ie10.win7.vagrant
  </code></pre>
  
  <p>After downloading, I get this error </p>
  
  <pre><code>bsdtar: Invalid central directory signature
  bsdtar: Error exit delayed from previous errors."
  </code></pre>
  
  <p>My questions are</p>
  
  <ol>
  <li><p>Does anyone know if that's because it's a zip? If so, is there a way I could automated the process of downloading it.</p></li>
  <li><p>Does vagrant cache this download somewhere I could reuse? It's a 4.5GB file so I don't wanna download it again. I have looked into the <code>~/.vagrant.d/boxes/win7-ie10/0</code> directory, but it is empty.</p></li>
  </ol>