PCNE Implementing network security Practice Question
This PCNE practice question tests your understanding of implementing network security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Which THREE components are required to set up Identity-Aware Proxy (IAP) for TCP forwarding to a VM?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A firewall rule that allows ingress from 35.235.240.0/20 to the VM on the desired port.
Option A is correct because IAP TCP forwarding requires that the VM allows ingress traffic from the IAP health-check and forwarding source IP range (35.235.240.0/20) on the desired TCP port. Without this firewall rule, the IAP proxy cannot establish a connection to the VM, even if the user is authenticated and authorized.
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.
✓
A firewall rule that allows ingress from 35.235.240.0/20 to the VM on the desired port.
Why this is correct
This IP range is used by IAP.
Related concept
Read the scenario before looking for a memorised answer.
✓
The user or group must have the IAP-secured Tunnel User role on the project.
Why this is correct
IAM roles grant access to use IAP.
Related concept
Read the scenario before looking for a memorised answer.
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that a VM must have a public IP to be accessed remotely, but IAP TCP forwarding specifically eliminates that requirement by tunneling through the internal network.
Detailed technical explanation
How to think about this question
IAP TCP forwarding works by establishing a secure tunnel from the user's device to the IAP service, which then proxies the connection to the VM's internal IP using the VPC network. The firewall rule allowing ingress from 35.235.240.0/20 is critical because this is the official IAP source range used for both health checks and forwarding; omitting it will cause connection timeouts. Additionally, the IAP-secured Tunnel User role grants the identity permission to initiate the tunnel, while the IAP API must be enabled to allow the service to operate in the project.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Implementing network security — This question tests Implementing network security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A firewall rule that allows ingress from 35.235.240.0/20 to the VM on the desired port. — Option A is correct because IAP TCP forwarding requires that the VM allows ingress traffic from the IAP health-check and forwarding source IP range (35.235.240.0/20) on the desired TCP port. Without this firewall rule, the IAP proxy cannot establish a connection to the VM, even if the user is authenticated and authorized.
What should I do if I get this PCNE 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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Question Discussion
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