The answer is to enable VPC Flow Logs for monitoring traffic patterns and to restrict ingress traffic with firewall rules. VPC Flow Logs capture metadata about IP traffic flowing through network interfaces, allowing you to detect anomalies, verify connectivity, and audit security policies without impacting performance. Restricting ingress traffic via firewall rules enforces the principle of least privilege by limiting access to only necessary ports and source IPs, directly reducing the attack surface. On the Google Professional Cloud Network Engineer exam, this pairing tests your understanding of both visibility and control—two pillars of VPC network security best practices. A common trap is confusing Flow Logs with a security control; they are a monitoring tool, not a blocking mechanism. Conversely, firewall rules are the primary enforcement point for ingress traffic. Remember the mnemonic: "Logs to watch, rules to block" to keep these distinct roles clear.
PCNE Configuring network services Practice Question
This PCNE practice question tests your understanding of configuring network services. 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.
Which TWO are best practices for securing a VPC network? (Choose 2.)
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use firewall rules to restrict ingress traffic to only necessary ports and IPs.
Option D is correct because firewall rules are the primary mechanism for controlling ingress traffic in a VPC. By restricting traffic to only necessary ports and source IPs, you minimize the attack surface and enforce the principle of least privilege. This is a fundamental security best practice for network segmentation and access control.
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 VPC Network Peering to connect to other projects.
Why it's wrong here
Peering is a connectivity option, not a security best practice.
Private Google Access is for accessing Google APIs privately, not primarily a security control.
✓
Use firewall rules to restrict ingress traffic to only necessary ports and IPs.
Why this is correct
This minimizes attack surface.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✓
Enable VPC Flow Logs to monitor traffic patterns.
Why this is correct
Flow logs help detect anomalies.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that default firewall rules are secure or that enabling features like Private Google Access or VPC Peering directly improve VPC security, when in fact they serve different purposes and can introduce risks if not configured correctly.
Detailed technical explanation
How to think about this question
VPC firewall rules are stateful, meaning that if you allow ingress traffic, the corresponding egress response is automatically allowed. This is implemented using connection tracking, which tracks the state of network connections (e.g., TCP, UDP, ICMP). In a real-world scenario, you might restrict SSH (port 22) to only specific admin IPs using a source range filter, preventing brute-force attacks from the internet.
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.
Configuring network services — This question tests Configuring network services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use firewall rules to restrict ingress traffic to only necessary ports and IPs. — Option D is correct because firewall rules are the primary mechanism for controlling ingress traffic in a VPC. By restricting traffic to only necessary ports and source IPs, you minimize the attack surface and enforce the principle of least privilege. This is a fundamental security best practice for network segmentation and access control.
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.
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?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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