- A
Use Cloud Armor to create a security policy that filters traffic from on-premises IP ranges on ports 443 and 8443, and attach it to the VPN gateway.
Why wrong: Cloud Armor applies to HTTP(S) load balancing, not VPN.
- B
Assign network tags to the Compute Engine VMs and create a firewall rule that allows traffic from the on-premises IP ranges on ports 443 and 8443 only to VMs with that tag.
Why wrong: Tags help but do not authenticate service accounts.
- C
Use Cloud NAT to provide outbound-only access from the VPC, and create firewall rules to block inbound traffic from on-premises.
Why wrong: Cloud NAT doesn't filter inbound traffic.
- D
Create VPC firewall rules that allow ingress from the on-premises IP ranges on ports 443 and 8443 to the target VMs. On the on-premises side, configure firewall rules to allow only traffic from the VPC IP ranges and require that the source VMs present a valid service account token, which can be verified using a proxy or by using Google Cloud's Identity-Aware Proxy (IAP) for TCP forwarding.
Correct approach: Firewall rules restrict ports, and IAP TCP forwarding or service account tokens provide authentication.
PCSE Practice Question: Configuring access within a cloud solution environment
This PCSE practice question tests your understanding of configuring access within a cloud solution environment. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Your company has a hybrid cloud environment with on-premises servers and Google Cloud. You are using Cloud VPN to connect the on-premises network to a VPC in us-central1. The on-premises network uses RFC 1918 addresses (10.0.0.0/8). The VPC has subnets in 10.0.0.0/8 as well, causing IP overlap. To resolve this, you have configured the VPC with a custom IP range of 172.16.0.0/12 and migrated some workloads. However, some legacy on-premises servers still need to access a specific set of Compute Engine VMs in the VPC. The security team requires that only authenticated service accounts from the VPC can access on-premises resources, and that traffic from on-premises to Google Cloud must be limited to specific ports (e.g., 443, 8443). You have set up a Cloud VPN tunnel with route-based VPN. What should you do to enforce these access controls?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Create VPC firewall rules that allow ingress from the on-premises IP ranges on ports 443 and 8443 to the target VMs. On the on-premises side, configure firewall rules to allow only traffic from the VPC IP ranges and require that the source VMs present a valid service account token, which can be verified using a proxy or by using Google Cloud's Identity-Aware Proxy (IAP) for TCP forwarding.
Option D is correct because it addresses both requirements: limiting traffic to specific ports (443, 8443) via VPC firewall rules, and enforcing authenticated service account access from the VPC to on-premises resources. Identity-Aware Proxy (IAP) for TCP forwarding allows on-premises servers to verify that source VMs present a valid service account token, ensuring only authenticated VPC workloads can initiate connections. This combination satisfies the security team's need for both port restriction and authentication without relying on IP-based trust alone.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Cloud Armor to create a security policy that filters traffic from on-premises IP ranges on ports 443 and 8443, and attach it to the VPN gateway.
Why it's wrong here
Cloud Armor applies to HTTP(S) load balancing, not VPN.
- ✗
Assign network tags to the Compute Engine VMs and create a firewall rule that allows traffic from the on-premises IP ranges on ports 443 and 8443 only to VMs with that tag.
Why it's wrong here
Tags help but do not authenticate service accounts.
- ✗
Use Cloud NAT to provide outbound-only access from the VPC, and create firewall rules to block inbound traffic from on-premises.
Why it's wrong here
Cloud NAT doesn't filter inbound traffic.
- ✓
Create VPC firewall rules that allow ingress from the on-premises IP ranges on ports 443 and 8443 to the target VMs. On the on-premises side, configure firewall rules to allow only traffic from the VPC IP ranges and require that the source VMs present a valid service account token, which can be verified using a proxy or by using Google Cloud's Identity-Aware Proxy (IAP) for TCP forwarding.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that firewall rules alone (like tags or Cloud Armor) can enforce authentication, when in reality they only filter by IP/port and cannot verify the identity of the source VM, which requires a solution like IAP or mutual TLS.
Detailed technical explanation
How to think about this question
IAP for TCP forwarding works by establishing a tunnel that requires the source VM to have a service account with the 'IAP-secured Tunnel User' role; the on-premises side can use a proxy (e.g., HAProxy or a custom application) to validate the JWT token presented by the VM, ensuring only authenticated requests pass. This approach decouples network-level access from identity, which is critical when IP ranges overlap (RFC 1918) and cannot be used for trust. In practice, this allows legacy on-premises servers to securely access specific Compute Engine VMs without re-IPing the entire network.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCSE question test?
Configuring access within a cloud solution environment — This question tests Configuring access within a cloud solution environment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create VPC firewall rules that allow ingress from the on-premises IP ranges on ports 443 and 8443 to the target VMs. On the on-premises side, configure firewall rules to allow only traffic from the VPC IP ranges and require that the source VMs present a valid service account token, which can be verified using a proxy or by using Google Cloud's Identity-Aware Proxy (IAP) for TCP forwarding. — Option D is correct because it addresses both requirements: limiting traffic to specific ports (443, 8443) via VPC firewall rules, and enforcing authenticated service account access from the VPC to on-premises resources. Identity-Aware Proxy (IAP) for TCP forwarding allows on-premises servers to verify that source VMs present a valid service account token, ensuring only authenticated VPC workloads can initiate connections. This combination satisfies the security team's need for both port restriction and authentication without relying on IP-based trust alone.
What should I do if I get this PCSE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This PCSE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCSE exam.
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