PCNE Implementing network security Practice Question
This PCNE practice question tests your understanding of implementing 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.
A company is designing a network architecture with multiple VPCs and on-premises connectivity via Cloud VPN. They want to avoid IP address conflicts and ensure secure communication. Which three best practices should they follow? (Choose three.)
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 unique RFC 1918 IP address ranges for each VPC.
Option B is correct because using unique RFC 1918 IP address ranges for each VPC prevents overlapping IP spaces, which is critical when connecting multiple VPCs and on-premises networks via Cloud VPN. Overlapping ranges would cause routing conflicts and make it impossible for Cloud Router and BGP to establish proper path selection, leading to dropped or misrouted traffic.
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 Cloud NAT for all outbound internet traffic from private VMs.
Why it's wrong here
Cloud NAT is for internet access, not for inter-VPC or on-premises communication.
✓
Use unique RFC 1918 IP address ranges for each VPC.
Why this is correct
Prevents IP overlap and routing issues.
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 Network Peering between all VPCs to enable direct communication.
Why it's wrong here
Peering adds complexity and potential transitive routing; not required for VPN connectivity.
✓
Set up firewall rules to allow only required traffic between VPCs and on-premises.
Why this is correct
Firewall rules enforce security by restricting traffic.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✓
Configure Cloud Router with BGP to advertise on-premises prefixes to Cloud VPN.
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 VPC Network Peering alone solves IP conflicts, but in reality, peering requires non-overlapping IP ranges to function correctly, and overlapping ranges will cause peering to fail or produce unpredictable routing behavior.
Detailed technical explanation
How to think about this question
Under the hood, Cloud VPN uses Cloud Router to exchange routes via BGP, and if two VPCs or the on-premises network share the same RFC 1918 subnet (e.g., 10.0.0.0/16), BGP will have multiple paths to the same prefix, causing asymmetric routing or route flapping. In real-world scenarios, organizations often use a structured IPAM (IP Address Management) plan, such as reserving a /16 per VPC from a larger corporate block, to ensure no overlaps and to simplify firewall rule creation for traffic filtering between environments.
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
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.
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: Use unique RFC 1918 IP address ranges for each VPC. — Option B is correct because using unique RFC 1918 IP address ranges for each VPC prevents overlapping IP spaces, which is critical when connecting multiple VPCs and on-premises networks via Cloud VPN. Overlapping ranges would cause routing conflicts and make it impossible for Cloud Router and BGP to establish proper path selection, leading to dropped or misrouted traffic.
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.
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 →
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.
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
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.