title: Mapping a custom subdomain ONLY with managed certificates on App Engine
body: <p>I am confused about the process for adding a custom subdomain <em>only</em> for App Engine, where App Engine manages the certificates. I'm following the steps in Google's documentation but this is messing up the mapping for my root domain. I want api.mydomain.com to point to my app engine instance, but the root of my domain and www. point to a website hosted on a different service. Note when I started this process I already had these DNS records:</p>
  
  <ul>
  <li><code>@ - A - &lt;an IP address where I'm serving my root domain&gt;</code></li>
  <li><code>www - CNAME - mydomain.com</code></li>
  </ul>
  
  <p>Going through the process in the app engine console it told me to add 4 A and 4 AAAA records at the <em>root</em> (i.e. @), and then a CNAME for my subdomain, e.g. after this was done I had</p>
  
  <ul>
  <li><code>@ - A - &lt;an IP address where I'm serving my root domain&gt;</code></li>
  <li><code>@ - A - 216.239.32.21</code></li>
  <li><code>@ - A - 216.239.34.21</code></li>
  <li><code>@ - A - 216.239.36.21</code></li>
  <li><code>@ - A - 216.239.38.21</code></li>
  <li><code>@ - AAAA - 2001:4860:4802:32::15</code></li>
  <li><code>@ - AAAA - 2001:4860:4802:34::15</code></li>
  <li><code>@ - AAAA - 2001:4860:4802:36::15</code></li>
  <li><code>@ - AAAA - 2001:4860:4802:38::15</code></li>
  <li><code>www - CNAME - mydomain.com.</code></li>
  <li><code>api - CNAME - ghs.googlehosted.com.</code></li>
  </ul>
  
  <p>The problem though is now some users, when they go to mydomain.com or www.mydomain.com, are getting App Engine's 404 page. This would seem to make sense because the A and AAAA records I added for App Engine are at the '@' level.</p>
  
  <p>Does anyone know what is wrong about this setup? Is it not possible to use managed certificates on a subdomain only on App Engine?</p>