title: Yum repositories don't work unless there are exceptions in the AWS firewall. How do I make the exceptions based on a DNS name?
body: <p>When I try to install something via yum (e.g., yum install java), I get the following:</p>
  
  <pre><code>Could not contact CDS load balancer rhui2-cds01.us-west-2.aws.ce.redhat.com, trying others.
  
  Could not contact any CDS load balancers: rhui2-cds01.us-west-2.aws.ce.redhat.com, rhui2-cds02.us-west-2.aws.ce.redhat.com.
  </code></pre>
  
  <p>Earlier today I installed various yum packages.  This evening I tried several, but none worked.</p>
  
  <p>This link explains that certain firewall rules need to be made:
  <a href="https://access.redhat.com/solutions/11214" rel="noreferrer">https://access.redhat.com/solutions/11214</a></p>
  
  <p>I don't have an explanation why all Yum install commands were working earlier today.  Several different ones later stopped working.  Here is the solution: via the AWS console, I opened all traffic over port 443 (inbound and outbound traffic). </p>
  
  <p>This isn't an ideal solution or a permanent solution. The security groups in the AWS console only permit filtering based on IP addresses and IP address ranges.  DNS names aren't part of the filtering.</p>
  
  <p>Using AWS, how can I open port 443 and port 80 to specific DNS names?</p>