For each ALB, create an A record that has a geolocation routing policy to route app.example.com to the IP addresses of the ALB. Configure a Route 53 HTTP health check that monitors each ALB by IP address. Associate the health check with the A records.

Create an A record that has a geolocation routing policy to route app.example.com to the IP addresses for both ALBs. Configure a Route 53 health check that monitors TCP port 80 for each ALB by IP address. Associate the health check with the A records.

Create an A record that has a latency-based routing policy to route app.example.com as an alias to one of the ALBs. Configure a Route 53 health check that monitors TCP port 80 for each ALB by IP address. Associate the health check with the A records.

For each ALB, create an A record that has a latency-based routing policy to route app.example.com as an alias to the ALB. Set the value for Evaluate Target Health to Yes for the records.