Answer By Deepseek

The correct answer is D. Here's why:

Explanation:

The scenario involves providing access to Google Cloud Storage for an application hosted on bare-metal servers in a private data center. The servers cannot have public IP addresses or direct internet access due to security policies. The goal is to follow Google-recommended practices to securely enable this access.

Why D is the correct choice:

Cloud VPN or Interconnect: This establishes a secure, private connection between your on-premises data center and Google Cloud. It ensures that traffic between your servers and Google Cloud Storage does not traverse the public internet.
Custom Route Advertisement: By using Cloud Router to advertise the specific IP range 199.36.153.4/30 (which includes the restricted.googleapis.com endpoint), you ensure that traffic to Google Cloud Storage is routed through the private connection.
DNS Configuration: Resolving *.googleapis.com as a CNAME to restricted.googleapis.com ensures that all API requests (including Cloud Storage) are directed to the restricted endpoint, which is accessible only through the private connection.

This approach adheres to Google's recommended practices for secure, private access to Cloud Storage without exposing your servers to the public internet.

Why the other options are incorrect:

A: This option suggests using public IP addresses and allowing egress traffic to specific IPs. However, it violates the security policy that prevents servers from having public IPs or internet access.
B: While this option uses a VPN tunnel, it introduces an unnecessary proxy server (Squid) in the VPC. This adds complexity and is not the most efficient or Google-recommended way to access Cloud Storage.
C: Migrating servers to Compute Engine is not necessary to access Cloud Storage. Additionally, creating an internal load balancer (ILB) with storage.googleapis.com as a backend is not a valid or recommended configuration.

Thus, D is the best and most secure solution.