Route 53 also supports health checks that allow us to determine the healthy and unhealthy AWS endpoints. It supports simple TCP port checks and more advanced HTTP and HTTPS health checks where it looks for either a 200 or 300 response with an additionally optional string matching functionality that can check your website for a specific string of text to determine if the site content is actually being served.
The health check can also determine the health based on the response time, a response threshold where we can define a number of required successful responses from the endpoint before determining it is healthy, and the CloudWatch alarm metrics collected for the AWS endpoint itself.
Health checks are performed from the global Route 53 endpoints and the service determines an endpoint healthy if more than 18% of the Route 53 endpoints report the service as healthy...