The nice thing about this solution, its not limited to RDS. I used RDS as an example as many are familiar with it and are known to the fact that it will change

The nice thing about this solution, its not limited to RDS. I used RDS as an example as many are familiar with it and are known to the fact that it will change AZ during maintenance events. Any hostname for a service in AWS that can relocate to another AZ (for whatever reason), can use this.