title: Which com.google.android.gms:play-services-ads version is compatible with com.android.support:appcompat-v7:27.1.1?
body: <p><strong>No duplicate:</strong>
  In my question I've already linked an answer similar to the supposed duplicate and explained, why I'm not looking for such an answer.</p>
  
  <p>Android Studio 3.2.1 automatically included</p>
  
  <pre><code>implementation 'com.android.support:appcompat-v7:27.1.1'
  </code></pre>
  
  <p>for my new app. I manually included </p>
  
  <pre><code>implementation 'com.google.android.gms:play-services-ads:17.1.1'
  </code></pre>
  
  <p>following the <a href="https://developers.google.com/admob/android/quick-start" rel="nofollow noreferrer">official guide</a>.</p>
  
  <p>The official guide from google seems to be outdated, as Android Studio immediately suggests using version 17.1.3 instead.</p>
  
  <p>In both cases however there is a red line under appcompat-v7 and a tooltip warning me that:</p>
  
  <blockquote>
    <p>All com.android.support libraries must use the exact same version specification (mixing versions can lead to runtime crashes). Found versions 27.1.1, 26.1.0.</p>
  </blockquote>
  
  <p>I do get the general problem here, play-services-ads transitively depends on an old version of some support library. <a href="https://stackoverflow.com/a/50565299/1785730">This answer</a> suggests to simply include the offending libraries manually in the correct version.</p>
  
  <p>However, I don't like this solution for two reasons:</p>
  
  <ol>
  <li><p>I simply don't want to deal with problems like this. There should be compatible versions available for the google libraries.</p></li>
  <li><p>At some point in the future I might have forgotten why I included all these libraries I don't even know what they do. I might want to update the appcompat and play-services-ads dependencies without thinking about all this again.</p></li>
  </ol>
  
  <p>Is version 17.1.3 the most recent version of play-services-ads as of now? Does that mean that play-services-ads is generally lagging behind? If so, I would prefer to downgrade appcompat-v7 instead of including some library versions manually.</p>
  
  <p>What would be the correct version of appcomat-v7 for play-services-ads version 17.1.3? Or maybe more generally asked: Which are the most recent versions of appcompat-v7 and play-services-ads that work together hassle free?</p>