title: why EC2 /etc/resolv.conf is always got empty, and rebooting the instance can fill the values, but later on it will be empty again
body: <p>Does anyone know the reason why the <code>/etc/resolv.conf</code> is got empty at sometimes and rebooting the instance, it can fill correct values into it, but after a while, it will be empty again, all the instances created by the same AMI have this issue.</p>
  
  <p>the instances are under a <code>VPC</code>, and we have enabled <code>DNS resolution</code> and <code>DNS hostnames</code>, and even <code>ClassicLink DNS Support</code>.</p>
  
  <p>and running <code>dhcpclient</code> doesn't work.</p>
  
  <p>Can someone help? Thanks</p>