title: Why are all the EC2 instances launched in the same availability zone?
body: <p>I have an AWS elastic beanstalk environment which contains an application load balancer that has 3 availability zones.</p>
  
  <p><a href="https://i.stack.imgur.com/oZMAN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oZMAN.png" alt="enter image description here"></a></p>
  
  <p>I'm wondering why all my 3 EC2 instances launched by elastic beanstalk are located in <code>ap-northeast-1c</code>.</p>
  
  <p>Is it possible to launch EC2 instances evenly in all the availability zones? I mean 1 instance per availability zone.</p>
  
  <p>The <em>Auto Scaling Group</em> in the <em>Configuration</em> section of elastic beanstalk contains 3 AZs.</p>
  
  <p><a href="https://i.stack.imgur.com/o2EPi.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/o2EPi.png" alt="enter image description here"></a></p>
  
  <p>But as you can see from the picture above, they are all grey, which means I'm not able to edit them. This is strange.</p>
  
  <p>If I open <em>EC2 Service</em> -> <em>Auto Scaling Group</em>, I found that the auto scaling group contains only 1 AZ. This is not consistent with the setting in elastic beanstalk.</p>
  
  <p><a href="https://i.stack.imgur.com/683sR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/683sR.png" alt="enter image description here"></a> </p>