On-prem servers over an existing Cloud VPN need access to Cloud Functions APIs while: keeping certain data confined to its project, avoiding internet egress for RFC1918 hosts, using on-prem DNS, and only exposing APIs compatible with VPC Service Controls. Which DNS/endpoint setup meets these requirements?

The correct option uses restricted.googleapis.com and the 199.36.153.4/30 range. This endpoint is specifically designed for use with VPC Service Controls, which is required to keep data confined to its project and restrict API access. It also ensures that RFC1918 hosts do not egress to the internet. The DNS configuration (A record for restricted.googleapis.com and CNAME for .googleapis.com) directs traffic to the private Google APIs. Routing on-premise traffic over the VPN tunnel and configuring on-prem firewalls correctly completes the secure, private access setup. The options using private.googleapis.com are incorrect because private.googleapis.com does not support VPC Service Controls, which is a key requirement. Removing the default internet gateway from the VPC is not necessary for this configuration and could disrupt other services.