- A
Use VPC Service Controls to create a service perimeter that blocks SSH traffic to all projects.
Why wrong: VPC Service Controls is for data exfiltration, not for firewall rules.
- B
Create a hierarchical firewall policy at the organization level with a rule that allows SSH for specific projects (using target service accounts or tags) at priority 1000, and a deny rule for all SSH at priority 2000.
Why wrong: Hierarchical firewall policies target VMs via tags or service accounts, not projects. Also, a lower-priority allow rule would apply to all matching VMs, not just specific projects.
- C
Create a network firewall policy for each VPC with a deny rule for SSH. Use service accounts for exceptions.
This allows per-VPC firewall policies with deny rules and service accounts for exceptions, enabling project-specific overrides.
- D
Create a hierarchical firewall policy at the organization level denying SSH (tcp:22). Then create a network firewall policy at each VPC allowing SSH for exempted projects.
Why wrong: Hierarchical deny rules cannot be overridden by VPC-level allow rules.
PCNE Network firewall policy Practice Question
This PCNE practice question tests your understanding of implementing vpc instances. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: network firewall policy. 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.
An organization has multiple projects under an organization node. They need to enforce a security policy that denies all inbound SSH traffic (tcp:22) to all VMs across all projects, but must allow certain projects to override this. Which approach should be used?
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 a network firewall policy for each VPC with a deny rule for SSH. Use service accounts for exceptions.
Option C is correct. Network firewall policies are applied at the VPC level and can be used to enforce a deny rule for SSH traffic. By using service accounts to identify VMs that should be exempt, you can allow certain projects (by assigning the appropriate service accounts) to override the deny. This approach allows per-project customization while maintaining a baseline deny. Option B is incorrect because hierarchical firewall policies do not support targeting entire projects directly; they rely on VM-level tags or service accounts, which would require manual tagging of every VM. Additionally, a hierarchical allow rule with a lower priority would apply to all VMs matching the target, not just the intended projects, potentially causing security gaps. Option A is incorrect because VPC Service Controls is designed for data exfiltration prevention, not traffic filtering. Option D is incorrect because a hierarchical deny rule cannot be overridden by a VPC-level allow rule.
Key principle: Network firewall policy
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 VPC Service Controls to create a service perimeter that blocks SSH traffic to all projects.
Why it's wrong here
VPC Service Controls is for data exfiltration, not for firewall rules.
- ✗
Create a hierarchical firewall policy at the organization level with a rule that allows SSH for specific projects (using target service accounts or tags) at priority 1000, and a deny rule for all SSH at priority 2000.
Why it's wrong here
Hierarchical firewall policies target VMs via tags or service accounts, not projects. Also, a lower-priority allow rule would apply to all matching VMs, not just specific projects.
- ✓
Create a network firewall policy for each VPC with a deny rule for SSH. Use service accounts for exceptions.
- ✗
Create a hierarchical firewall policy at the organization level denying SSH (tcp:22). Then create a network firewall policy at each VPC allowing SSH for exempted projects.
Why it's wrong here
Hierarchical deny rules cannot be overridden by VPC-level allow rules.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Network firewall policy
- Service account
- Priority evaluation
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
Network firewall policy
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Visual reference
What to study next
Got this wrong? Here's your next step.
Review network firewall policy, then practise related PCNE questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this PCNE question test?
Implementing VPC Instances — This question tests Implementing VPC Instances — Network firewall policy.
What is the correct answer to this question?
The correct answer is: Create a network firewall policy for each VPC with a deny rule for SSH. Use service accounts for exceptions. — Option C is correct. Network firewall policies are applied at the VPC level and can be used to enforce a deny rule for SSH traffic. By using service accounts to identify VMs that should be exempt, you can allow certain projects (by assigning the appropriate service accounts) to override the deny. This approach allows per-project customization while maintaining a baseline deny. Option B is incorrect because hierarchical firewall policies do not support targeting entire projects directly; they rely on VM-level tags or service accounts, which would require manual tagging of every VM. Additionally, a hierarchical allow rule with a lower priority would apply to all VMs matching the target, not just the intended projects, potentially causing security gaps. Option A is incorrect because VPC Service Controls is designed for data exfiltration prevention, not traffic filtering. Option D is incorrect because a hierarchical deny rule cannot be overridden by a VPC-level allow rule.
What should I do if I get this PCNE question wrong?
Review network firewall policy, then practise related PCNE questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Network firewall policy
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Last reviewed: Jul 4, 2026
This PCNE 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 PCNE exam.
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