title: FCM Error: java.net.UnknownHostException: fcm.googleapis.com
body: <p>I am making a <code>POST</code> call to <code>https://fcm.googleapis.com/fcm/send</code> to send push notification to a device using FCM (Firebase cloud Messaging). </p>
  
  <p>But I am getting an error that says </p>
  
  <pre><code>java.net.UnknownHostException: fcm.googleapis.com. 
  </code></pre>
  
  <p>Could you help find out the cause?</p>