Google Updated Professional-Cloud-Security-Engineer Exam Questions and Answers by mabli

https://cloud.google.com/vpc/docs/firewalls#service-accounts-vs-tags

https://cloud.google.com/vpc/docs/firewalls#service-accounts-vs-tags

A service account represents an identity associated with an instance. Only one service account can be associated with an instance. You control access to the service account by controlling the grant of the Service Account User role for other IAM principals. For an IAM principal to start an instance by using a service account, that principal must have the Service Account User role to at least use that service account and appropriate permissions to create instances (for example, having the Compute Engine Instance Admin role to the project).

To connect Compute Engine instances within a Google Cloud Platform project to workloads running in a dedicated server room that can only be accessed from within the private company network, you can use the following approaches:

Cloud VPN: Cloud VPN securely connects your on-premises network to your Google Cloud Virtual Private Cloud (VPC) network through an IPsec VPN connection. This enables secure communication between your GCP instances and your on-premises workloads over the internet.

Cloud Interconnect: Cloud Interconnect provides direct physical connections between your on-premises network and Google's network. It offers higher bandwidth and lower latency compared to Cloud VPN, making it suitable for workloads that require fast and reliable connectivity.

Both Cloud VPN and Cloud Interconnect allow you to securely connect your on-premises environments to Google Cloud, ensuring that the workloads remain within the private company network.

References

Cloud VPN Overview

Cloud Interconnect Overview

For external applications (outside of Google Cloud) to access resources securely, Workload Identity Federation (WIF) is the modern standard.3 It avoids the use of permanent service account keys and relies on external identity providers (OIDC or SAML) to exchange short-lived Google Cloud tokens.

According to Google Cloud Documentation (Workload Identity Federation):

"You can use Workload Identity Federation to grant on-premises or multi-cloud workloads access to Google Cloud resources without using a service account key. This reduces the risk associated with long-lived service account keys and simplifies the implementation of security best practices."

Key points:

It allows external identities (from AWS, Azure, or OIDC/SAML providers) to assume a Google IAM role.

The access is short-lived and scoped to specifically what the application needs (e.g., storage.objects.create).

Why other options are incorrect:

A is incorrect: Long-lived service account keys are a security liability.

B is incorrect: While a proxy works, it adds architectural complexity and overhead compared to direct federation.

C is incorrect: IP-based ACLs are weak because IPs can be spoofed or changed, and Cloud Storage ACLs do not provide robust identity-based security for public-facing apps.

The problem is that the on-premises developers cannot resolve the Artifact Registry hostname, and they have no route to the internet. This is a classic DNS resolution problem in a hybrid network using private API access.

Artifact Registry is a Google-managed service, and its hostname (e.g., us-west1-docker.pkg.dev) resolves to a Google API domain. To access Google services privately from an on-premises network without an internet route, the traffic must be directed to Private Google Access IP ranges.

Issue: The on-premises DNS cannot resolve the Google service domain to the required private IP range.

Solution: The on-premises DNS needs a record (or a forwarding rule) to resolve the Google service domain to the dedicated IP ranges used for Private Google Access, specifically restricted.googleapis.com or private.googleapis.com (which provide the IP addresses for private access).

Extracts (Conceptual Basis):

"To direct traffic privately, you must ensure that your on-premises network's DNS is configured to resolve Google API and service domain names to the IP address range for Private Google Access." (Source 1.1)

"The IP addresses for private.googleapis.com are used for Private Google Access. To enable on-premises hosts to access Google APIs and services using this method, you must configure on-premises DNS to resolve requests for Google API domain names to the IP address range for private.googleapis.com." (Source 1.2)

Option B is incorrect because Private Google Access (PGA) is enabled on the VPC subnet, allowing VMs within the VPC to access Google APIs. However, the problem is with the on-premises developers; the on-premises DNS must be configured to resolve the hostname correctly.