This reference architecture diagram illustrates an OCI Region including an Availability Domain with two VCNs; hub.example.com and spoke.example.com each including a subnet.

Both subnets host Compute and other Resources and are connected with an LPG (local Peering Gateway) and a Private DNS resolver. The subnet in VCN hub.example.com connects to Customer-Premises and On-Premises DNS using VPN/FastConnect.