title: AWS latency between Zones within a same Region
body: <p>I have an <code>EC2</code> and <code>RDS</code> in the same region <code>US East(N. Virginia)</code> but both resources are in different zones; RDS in <code>us-east-1a</code> and EC2 in <code>us-east-1b</code>.</p>
  
  <p>Now the question is that <strong>if I put both resources within the same <code>zone</code> then would it speed up the data transfer to/from DB</strong>? I receive daily around 20k-30k entries from app to this instance.</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>I read <a href="https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-regions-availability-zones" rel="noreferrer">here</a> that: </p>
  
  <blockquote>
    <p>Each Availability Zone is isolated, but the Availability Zones in a region are connected through low-latency links. </p>
  </blockquote>
  
  <p>Now I am wondering if these <code>low-latency links</code> are very minor or should I consider shifting my resources in the same zone to speed up the data transfer?</p>
  
  <p><a href="https://i.stack.imgur.com/RtXVM.png" rel="noreferrer"><img src="https://i.stack.imgur.com/RtXVM.png" alt="enter image description here"></a></p>
  
  <p><strong>Conclusion</strong></p>
  
  <p>As discussed in answers and comments:</p>
  
  <ul>
  <li>Since I have only one instance of <code>EC2</code> and <code>RDS</code>, failure of one service in a <code>zone</code> will affect the whole system. So there is no advantage to keeping them in a separate zone.</li>
  <li>Even though <code>zones</code> are connected together with <code>low-latency links</code> but there is still some latency which is <strong>neglectable</strong> in my case.</li>
  <li>There is also a minor data transfer charge of <strong>USD 0.01/GB</strong> between <code>EC2</code> and <code>RDS</code> in different zones.</li>
  </ul>