title: apt-get update is not working inside docker container
body: <p>I have created the container using the ubuntu:14.04.
  I have set proxies in the docker file configuration.
  When i start the conatiner and type command apt-get update it is giving me error.</p>
  
  <pre><code>root@4a7043e2f675:/# apt-get update
  </code></pre>
  
  <pre>
  0% [Connecting to archive.ubuntu.com]
  </pre>
  
  <p>will stuck here and after for a while gives error as follow :</p>
  
  <pre>
  Err http://archive.ubuntu.com trusty InRelease
  
  Err http://archive.ubuntu.com trusty Release.gpg
    Could not resolve 'archive.ubuntu.com'
  Reading package lists... Done
  W: Failed to fetch http:// archive.ubuntu.com/ubuntu/dists/trusty/InRelease
  
  W: Failed to fetch http:// archive.ubuntu.com/ubuntu/dists/trusty/Release.gpg  Could not resolve 'archive.ubuntu.com'
  
  W: Some index files failed to download. They have been ignored, or old ones used instead.
  </pre>
  
  <p>please provide me solution people.</p>