Creating a secondary site in another region within the same country with Amazon Route 53 managing traffic between regions ensures that the application stays online even if the primary region fails. Amazon Route 53 can detect if a region is down and route traffic to another available region that also resides within the country, thus maintaining compliance and high availability. This approach contributes to a fault-tolerant architecture by preventing a single region's failure from causing application downtime. Using multiple Availability Zones alone is not sufficient because it doesn't protect against a whole region failure. Adding read replicas in other Availability Zones does not address region-level disaster recovery if the read replicas are all within the same region. Expanding to only one additional Availability Zone will not prevent downtime if that zone is in the same region as the other two, as the requirement is to survive a full-region outage.