- A
Create an ingress firewall rule denying all traffic from the subnet CIDR, then create a higher priority rule allowing traffic from the health check range.
Why wrong: This approach would require careful priority management; if the deny rule has higher priority than the allow rule, the allow rule would be ineffective.
- B
Use hierarchical firewall policies to enforce the rule at the organization level.
Why wrong: Hierarchical firewall policies are used for centralized rule management across projects, not for restricting traffic within a single subnet.
- C
Use VPC firewall rules with target tags to apply rules only to instances that need health checks.
Why wrong: Target tags help apply rules to specific instances but do not restrict traffic within the subnet; they are not the best solution for this scenario.
- D
Create a firewall rule that allows only health check traffic and deny all other ingress by default using implied deny.
This leverages the implied deny rule at the end of the firewall evaluation, ensuring that only allowed health check traffic is permitted, and all other traffic is denied by default.
Quick Answer
The best approach is to create a firewall rule that allows only the load balancer health check traffic and rely on the implied deny rule to block all other ingress within the VPC subnet. This works because GCP VPC firewall rules are evaluated in order of priority, and an implied deny rule exists at the lowest priority, automatically dropping any traffic not explicitly allowed. By crafting a single allow rule for the health check range and leaving the implied deny in place, you achieve subnet traffic isolation without complex rule management. On the Google Professional Cloud Security Engineer exam, this scenario tests your understanding of GCP’s default-deny posture and the priority-based evaluation of firewall rules—a common trap is assuming you need a separate deny rule, which would actually require a higher priority than the allow rule to be effective. Remember the memory tip: “One allow, implied deny—no extra rules, traffic stays shy.”
PCSE Practice Question: Managing operations in a cloud solution environment
This PCSE practice question tests your understanding of managing operations in a cloud solution environment. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
A company has a VPC with several subnets. They want to restrict traffic between instances in the same subnet using firewall rules while allowing traffic from a specific load balancer health check range. What is the best approach?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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 firewall rule that allows only health check traffic and deny all other ingress by default using implied deny.
Option C is correct because GCP VPC firewall rules have an implied deny at the end; therefore, allowing only the health check traffic and relying on the implied deny for other traffic is the simplest and most secure approach. Option A is incorrect because a deny rule with higher priority than an allow rule would block the allowed traffic. Option B is incorrect because target tags are useful but do not directly address restricting internal subnet traffic. Option D is incorrect because hierarchical policies are for organization-level rules, not for this specific subnet restriction.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create an ingress firewall rule denying all traffic from the subnet CIDR, then create a higher priority rule allowing traffic from the health check range.
Why it's wrong here
This approach would require careful priority management; if the deny rule has higher priority than the allow rule, the allow rule would be ineffective.
- ✗
Use hierarchical firewall policies to enforce the rule at the organization level.
Why it's wrong here
Hierarchical firewall policies are used for centralized rule management across projects, not for restricting traffic within a single subnet.
- ✗
Use VPC firewall rules with target tags to apply rules only to instances that need health checks.
Why it's wrong here
Target tags help apply rules to specific instances but do not restrict traffic within the subnet; they are not the best solution for this scenario.
- ✓
Create a firewall rule that allows only health check traffic and deny all other ingress by default using implied deny.
Why this is correct
This leverages the implied deny rule at the end of the firewall evaluation, ensuring that only allowed health check traffic is permitted, and all other traffic is denied by default.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
CIDR notation defines the prefix length.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Trap categories for this question
Scenario analysis trap
Target tags help apply rules to specific instances but do not restrict traffic within the subnet; they are not the best solution for this scenario.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCSE subnetting questions on CIDR, address ranges, and subnet selection.
- →
Managing operations in a cloud solution environment — study guide chapter
Learn the concepts, then practise the questions
- →
Managing operations in a cloud solution environment practice questions
Targeted practice on this topic area only
- →
All PCSE questions
500 questions across all exam domains
- →
Google Professional Cloud Security Engineer study guide
Full concept coverage aligned to exam objectives
- →
PCSE practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related PCSE practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Configuring network security practice questions
Practise PCSE questions linked to Configuring network security.
Configuring access within a cloud solution environment practice questions
Practise PCSE questions linked to Configuring access within a cloud solution environment.
Ensuring data protection practice questions
Practise PCSE questions linked to Ensuring data protection.
Managing operations in a cloud solution environment practice questions
Practise PCSE questions linked to Managing operations in a cloud solution environment.
Supporting compliance requirements practice questions
Practise PCSE questions linked to Supporting compliance requirements.
PCSE fundamentals practice questions
Practise PCSE questions linked to PCSE fundamentals.
PCSE scenario practice questions
Practise PCSE questions linked to PCSE scenario.
PCSE troubleshooting practice questions
Practise PCSE questions linked to PCSE troubleshooting.
Practice this exam
Start a free PCSE practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this PCSE question test?
Managing operations in a cloud solution environment — This question tests Managing operations in a cloud solution environment — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Create a firewall rule that allows only health check traffic and deny all other ingress by default using implied deny. — Option C is correct because GCP VPC firewall rules have an implied deny at the end; therefore, allowing only the health check traffic and relying on the implied deny for other traffic is the simplest and most secure approach. Option A is incorrect because a deny rule with higher priority than an allow rule would block the allowed traffic. Option B is incorrect because target tags are useful but do not directly address restricting internal subnet traffic. Option D is incorrect because hierarchical policies are for organization-level rules, not for this specific subnet restriction.
What should I do if I get this PCSE question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCSE subnetting questions on CIDR, address ranges, and subnet selection.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 24, 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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.