title: Docker container can reach DNS but not resolve hosts
body: <p>I'm having an interesting problem running docker containers: out of the blue, I'm not able to resolve DNS from within the container.</p>
  
  <p>Here's a rundown:  </p>
  
  <ol>
  <li><p>Nothing is resolving; apt-get, pip, one-off ping containers, etc. Running <code>docker run -it --dns=8.8.8.8 ubuntu ping www.google.com</code> results in <code>ping: unknown host www.google.com</code> both with and without the <code>--dns</code> flag.</p></li>
  <li><p>I can reach 8.8.8.8 both from inside and outside the containers.  <code>docker run -it ubuntu ping 8.8.8.8</code> works.</p></li>
  <li><p>I've configured the containers to use both 8.8.8.8, 8.8.8.4, and my local network DNS servers (in various permutations) both by editing <code>/etc/sysconfig/docker</code> to add <code>DOCKER_OPTS="--dns 8.8.8.8 --dns 8.8.8.4"</code> and by setting the <code>--dns 8.8.8.8</code> flag on the containers at runtime. <code>systemctl restart docker</code> was run between each change.  </p></li>
  <li><p><code>ip_forward</code> is enabled. (see <a href="https://github.com/docker/docker/issues/490">here</a>)</p></li>
  <li><p>I've done a full reset as specified <a href="https://github.com/docker/docker/issues/866#issuecomment-19218300">here</a>.</p></li>
  </ol>
  
  <p>I'm running Fedora 21, docker client version 1.5.0.</p>
  
  <p>Any ideas? I'm at a complete loss as to what's preventing docker from accessing the Internet successfully.</p>