Classic Route 53 multi-account DNS

Share one private hosted zone across three accounts and two regions — classic VPC association authorization, no Profiles or RAM.

One network-owned private hosted zone (platform.demo.local) associated with owner, cross-account, and cross-region VPCs after CreateVPCAssociationAuthorization and AssociateVPCWithHostedZone.

Covers four association scenarios and when classic PHZ sharing fits versus Route 53 Profiles or RAM.