The image shows Oracle Database@Google Cloud with private DNS and multiple database services. An ODB network spans Google Cloud and an OCI Region. The environment includes a Google Cloud Project with a VPC and a Region/Zone, and an Oracle Database@Google Cloud child site.

Google Cloud components include:

Application subnet hosting an application that connects to databases.
Cloud DNS, which issues and receives forwarded DNS queries.

Oracle Database@Google Cloud child site includes:

VCN that contains a client subnet.
Database services available in the client subnet:
- Oracle Exadata Database Service
- Oracle Base Database Service
- Oracle Autonomous Database
Network Security Group (NSG) for access control.
Two private DNS endpoints:
- Private DNS Listener Endpoint
- Private DNS Forwarder Endpoint

OCI region includes:

Control plane that manages the database services.
OCI DNS for authoritative name resolution.
DNS and traffic flow:
- Cloud DNS uses a DNS forwarding rule to send queries to the Private DNS Listener Endpoint.
- The Private DNS Forwarder Endpoint sends DNS queries to OCI DNS using a DNS forwarding rule and returns responses.
- Database service hostnames resolve privately through these endpoints.
- The application communicates privately with the database services inside the VCN, with access governed by the NSG.