A company runs an active application in one Region and a ready standby in another. It wants Route 53 to return the standby endpoint after health evaluation marks the primary unhealthy. Which routing policy is most suitable?

1. Weighted routing with permanently equal weights and no health checks.
2. Geolocation routing alone, with both Regions configured as healthy by default.
3. A private hosted zone in the primary VPC with no DNS records for the standby.
4. Failover routing with primary and secondary records and appropriate health evaluation.