To provide on-premises hosts with access to Google APIs without using public IP addresses or the public internet, Google Cloud provides Private Google Access for on-premises hosts. This feature allows traffic to stay within the Google network via Cloud Interconnect or Cloud VPN.
According to the official Google Cloud Documentation (Configuring Private Google Access for on-premises hosts):
"Private Google Access for on-premises hosts provides a way for on-premises systems to connect to Google APIs and services by routing traffic through a Cloud VPN tunnel or Cloud Interconnect attachment (VLAN).
On-premises hosts don't need public IP addresses; instead, they use internal IP addresses." Key Implementation Steps:
* Network Connectivity: Ensure your on-premises network is connected to your VPC via Cloud Interconnect or VPN.
* DNS Configuration: You must configure your on-premises DNS to map API requests (like storage.
googleapis.com) to special IP ranges. There are two primary options:
* private.googleapis.com: Resolves to 199.36.153.8/30. This range supports most Google APIs but only those that are VPC-Service Control compatible.
* restricted.googleapis.com: Resolves to 199.36.153.4/30. This is required specifically when using VPC Service Controls (VPC-SC) to ensure data cannot be exfiltrated to services outside the perimeter.
* Routing: You must configure custom static routes in your VPC or use BGP to advertise the 199.36.153.8
/30 (or 199.36.153.4/30) range back to your on-premises router.
Why other options are incorrect:
* A is incorrect: Shared VPC is used to share a network across multiple Google Cloud projects, not to extend a VPC directly to on-premises hardware.
* C is incorrect: While the IP range 199.36.153.8/30 is correct for private.googleapis.com, Cloud NAT is used for outbound internet access from VPC instances without external IPs; it does not facilitate private on-premises-to-API connectivity.
* D is incorrect: VPC Peering connects two VPCs within Google Cloud. You cannot "peer" an on- premises data center directly via VPC Peering; you must use Interconnect or VPN.
Reference: * Google Cloud Security Engineer Study Guide, Chapter 4: Configuring Network Security.
Google Cloud Documentation: "Configure Private Google Access for on-premises hosts" (https://cloud.
google.com/vpc/docs/configure-private-google-access-on-premises).