title: EC2 instance attached to a load balancer is showing Unhealthy status
body: <p>I created a load balancer and assigned it one of the running EC2 instance. After creation, I navigated to Target Group section in the AWS Console under Load Balancing and when I selected the target group that was assigned to the load balancer, it shows registered instance status as "Unhealthy" and there was a message above registered instance pane that says "None of these Availability Zones contains a healthy target. Requests are being routed to all targets". While creating the load balancer, I selected all the subnets (availability zones).
  settings I used for health check are mentioned below,</p>
  
  <ul>
  <li>Protocol: HTTP</li>
  <li>Path: /healthcheck.html</li>
  <li>Port: traffic port</li>
  <li>Healthy threshold: 3</li>
  <li>Unhealthy threshold: 2</li>
  <li>Timeout: 5</li>
  <li>Interval: 10</li>
  <li>Success codes: 200</li>
  </ul>
  
  <p>So why does my registered instance status as "Unhealthy" and how can I rectify/resolve that to change the status to "In-service"?</p>