ELB Health Check return code

You can have TCP and HTTP health checks. A TCP health check will simply check if the web page exists (can be pinged essentially) a HTTP health check needs to return a 200 to pass the health check. More can be found here:
http://stackoverflow.com/questions/23689333/how-to-instruct-an-aws-elb-to-consider-a-health-check-that-returns-a-403-code-as

ELB HTML file health check file

If you are running Apache, you will need to place the help check file for ELB in /var/www/html.  You can use the default web page (index.html). However, I normally use another file incase the index.html file gets removed for some reason.  Also, another file like ping.html indicates to a DevOps person that this is for the ELB health check.