Exam AWS-SysOps topic 1 question 327 discussion

For both latency alias records, you set the value of Evaluate Target Health to Yes. This causes Route 53 to determine whether there are any healthy resources in a region before trying to route traffic there. If not, Route 53 chooses a healthy resource in the other region. https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/dns-failover-complex-configs.html

By using Amazon Route 53's Latency Based Routing (LBR), the Administrator can configure a record set that directs traffic to the ELB in the region with the lowest latency. This allows users to be automatically routed to the region with the best performance. Additionally, setting up health checks on each ELB ensures that if one region experiences network connectivity issues or becomes unavailable, Route 53 will route traffic to the ELB in a different region with better connectivity.