title: How does Auto Scaling "place" instances when used with multiple availability zones?
body: <p>Consider the case when an Auto Scaling group is configured to span multiple availability zones (such as in <a href="http://docs.aws.amazon.com/AutoScaling/latest/DeveloperGuide/US_AddAvailabilityZone.html">this scenario</a>). When a new Amazon EC2 instance should be added to the scaling group (scale out) based on demand, how does Auto Scaling decide in which availability zone the instance will be placed? The one that has the smaller number of instances?</p>
  
  <p>Thanks for your help.</p>