title: ELB, EC2, Instance has failed at least the UnhealthyThreshold number of health checks consecutively
body: <p>I am configuring ELB with EC2 in AWS and run into "Instance has failed at least the UnhealthyThreshold number of health checks consecutively" error to cause the instance out of service. I have checked,</p>
  
  <p>1) as I m using 8080 for security check port and my path is "/index.html". I test the link <code>http://ec2DNSname:8080/index.html</code> in the browser, it returns,</p>
  
  <pre><code>Response header:
  HTTP/1.1 200 OK
  X-Powered-By: Express
  Accept-Ranges: bytes
  ETag: "150-1420697739000"
  Date: Thu, 08 Jan 2015 06:16:21 GMT
  Cache-Control: public, max-age=0
  Last-Modified: Thu, 08 Jan 2015 06:15:39 GMT
  Content-Type: text/html; charset=UTF-8
  Content-Length: 150
  Vary: Accept-Encoding
  Connection: keep-alive
  </code></pre>
  
  <p>2) In my EC2 config, I allow the the inbound TCP traffic on 8080 from any machines</p>
  
  <p>Any other possible cause of failing the health check?</p>
  
  <p>Thanks
  Hammer</p>