- A
Denied, because Rule 2 has a lower priority number and explicitly denies traffic from 10.0.0.0/8
Correct: Rule 2 has priority 500, which is evaluated before Rule 1 (1000) and Rule 3 (2000). Since it matches, the deny action is applied.
- B
Denied, because Rule 3 has a higher priority number and denies traffic from 192.168.0.0/16
Why wrong: Rule 3 allows traffic, and its source range does not include 10.0.0.5. It does not affect this request.
- C
Allowed, because Rule 1 has a lower priority number and allows all traffic
Why wrong: Rule 1 has priority 1000, which is higher than Rule 2 (500). Rule 2 is evaluated first and denies the traffic.
- D
Allowed, because Rule 3 has a higher priority number and allows traffic from 192.168.0.0/16
Why wrong: Rule 3 has priority 2000, which is lower priority (higher number) than Rule 2. Since Rule 2 matches, it applies and denies.
Quick Answer
The answer is denied, because Rule 2 with priority 500 explicitly blocks traffic from the 10.0.0.0/8 range, and the user’s IP 10.0.0.5 falls within that source. In Google Cloud VPC firewall rule priority evaluation, lower numerical priority values are evaluated first, meaning a rule with priority 500 takes precedence over rules with higher numbers like 1000 or 2000, regardless of whether those later rules would allow the traffic. This concept is critical for the Google Professional Cloud Security Engineer exam, where you must understand that the first matching rule—not the most specific or most permissive—determines the action, making it a common trap to assume a broader allow rule overrides a higher-priority deny. A reliable memory tip is “lowest number wins the fight,” so when you see a deny rule with a lower priority number than an allow rule, the deny will always be evaluated and applied first.
PCSE Configuring network security Practice Question
This PCSE practice question tests your understanding of configuring network security. 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.
You have a Compute Engine VM that hosts a custom application. The VM has a tag 'app-server' and is in a VPC network with the following firewall rules (priority order from lowest to highest):
Rule 1: Priority 1000, direction INGRESS, source 0.0.0.0/0, target tag 'app-server', protocol tcp:80, action allow Rule 2: Priority 500, direction INGRESS, source 10.0.0.0/8, target tag 'app-server', protocol tcp:80, action deny Rule 3: Priority 2000, direction INGRESS, source 192.168.0.0/16, target tag 'app-server', protocol tcp:80, action allow
A user from IP 10.0.0.5 tries to access the application on port 80. Will the request be allowed or denied?
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
Denied, because Rule 2 has a lower priority number and explicitly denies traffic from 10.0.0.0/8
Rule 2 has a priority of 500, which is lower (higher priority) than Rule 1 (priority 1000) and Rule 3 (priority 2000). Since the source IP 10.0.0.5 falls within the 10.0.0.0/8 range, Rule 2 matches first and explicitly denies the traffic. In Google Cloud VPC firewall rules, lower priority numbers are evaluated first, and the first matching rule determines the action.
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.
- ✓
Denied, because Rule 2 has a lower priority number and explicitly denies traffic from 10.0.0.0/8
Why this is correct
Correct: Rule 2 has priority 500, which is evaluated before Rule 1 (1000) and Rule 3 (2000). Since it matches, the deny action is applied.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Denied, because Rule 3 has a higher priority number and denies traffic from 192.168.0.0/16
Why it's wrong here
Rule 3 allows traffic, and its source range does not include 10.0.0.5. It does not affect this request.
- ✗
Allowed, because Rule 1 has a lower priority number and allows all traffic
Why it's wrong here
Rule 1 has priority 1000, which is higher than Rule 2 (500). Rule 2 is evaluated first and denies the traffic.
- ✗
Allowed, because Rule 3 has a higher priority number and allows traffic from 192.168.0.0/16
Why it's wrong here
Rule 3 has priority 2000, which is lower priority (higher number) than Rule 2. Since Rule 2 matches, it applies and denies.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that higher priority numbers mean higher precedence, but in Google Cloud VPC firewall rules, lower numeric priority values are evaluated first, so candidates must remember that priority 500 is evaluated before priority 1000.
Detailed technical explanation
How to think about this question
Google Cloud VPC firewall rules are stateful and evaluated in order of priority (lower number = higher priority). The first rule that matches the source IP, target tag, protocol, and port determines whether traffic is allowed or denied. This is similar to how iptables rules are processed, but with a simpler priority-based model. In practice, this design allows administrators to create explicit deny rules for specific subnets while allowing broader access, which is critical for security segmentation.
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 network security — This question tests Configuring network security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Denied, because Rule 2 has a lower priority number and explicitly denies traffic from 10.0.0.0/8 — Rule 2 has a priority of 500, which is lower (higher priority) than Rule 1 (priority 1000) and Rule 3 (priority 2000). Since the source IP 10.0.0.5 falls within the 10.0.0.0/8 range, Rule 2 matches first and explicitly denies the traffic. In Google Cloud VPC firewall rules, lower priority numbers are evaluated first, and the first matching rule determines the action.
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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