Question
In AWS, for Route 53, when you choose the [...] routing policy for your DNS records (i.e. you specifiy multpile A records with the same Name/Type but different values, e.g. different EC2 or ELB DNS values), Route 53 will return the value to the user based on the shortest response time from user location to the region (auto-detected in the Route53 GUI when you choose this routing policy) where the target resource (e.g. EC2 instance, ELB) is located.