- A
Create a Cloud NAT gateway in each zone and configure region-specific NAT rules.
Regional NAT with gateways per zone provides automatic failover and high availability.
- B
Create a Cloud NAT gateway in one zone and configure an instance tag-based route to the gateway.
Why wrong: Single-zonal gateway is not highly available; if the zone fails, internet access is lost.
- C
Enable Private Google Access on the subnets and configure a Cloud NAT gateway in one zone.
Why wrong: Private Google Access only allows access to Google APIs, not external APIs; also a single NAT gateway lacks high availability.
- D
Assign external IP addresses to each instance and create appropriate firewall rules.
Why wrong: Requires external IPs, increasing attack surface and management overhead; no high availability mechanism needed.
Quick Answer
The answer is to create a Cloud NAT gateway in each zone and configure region-specific NAT rules. This design ensures Cloud NAT high availability per zone by eliminating cross-zone traffic and providing automatic failover: if a zone fails, its local gateway goes down, but instances in healthy zones continue using their own gateway without manual intervention. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding that a single regional Cloud NAT gateway is not highly available per zone—it creates a single point of failure for all zones. A common trap is choosing a regional gateway with a single NAT IP, which fails if that zone goes down. The key memory tip is “one NAT per zone, no failover alone”—each zone gets its own gateway to maintain local, resilient outbound connectivity without external IPs.
PCNE Practice Question: Designing, planning, and prototyping a GCP network
This PCNE practice question tests your understanding of designing, planning, and prototyping a gcp network. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 Compute Engine instances without external IP addresses that need to access external APIs. The instances are in multiple zones within a region, and each zone has a subnet. The company wants a cost-effective and highly available solution that does not require manual failover. What should they do?
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 Cloud NAT gateway in each zone and configure region-specific NAT rules.
A Cloud NAT gateway per zone provides highly available outbound connectivity for instances without external IPs. By placing a gateway in each zone, traffic from instances in that zone uses the local gateway, avoiding cross-zone hops and ensuring automatic failover if a zone fails. This meets the cost-effective and no-manual-failover requirements without needing instance-level external IPs.
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.
- ✓
Create a Cloud NAT gateway in each zone and configure region-specific NAT rules.
Why this is correct
Regional NAT with gateways per zone provides automatic failover and high availability.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a Cloud NAT gateway in one zone and configure an instance tag-based route to the gateway.
Why it's wrong here
Single-zonal gateway is not highly available; if the zone fails, internet access is lost.
- ✗
Enable Private Google Access on the subnets and configure a Cloud NAT gateway in one zone.
- ✗
Assign external IP addresses to each instance and create appropriate firewall rules.
Why it's wrong here
Requires external IPs, increasing attack surface and management overhead; no high availability mechanism needed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a single Cloud NAT gateway is sufficient for high availability, but the PCNE exam expects zone-level redundancy to avoid a single point of failure and to meet the 'no manual failover' requirement.
Detailed technical explanation
How to think about this question
Cloud NAT uses Andromeda, Google's network virtualization stack, to perform source network address translation (SNAT) for outbound packets. Each Cloud NAT gateway is regional but zone-scoped; creating one per zone ensures that egress traffic stays within the zone, reducing latency and avoiding cross-zone bandwidth charges. In a real-world scenario, if an instance in zone A sends traffic through a NAT in zone B, the return path may traverse inter-zone links, increasing cost and latency—hence per-zone gateways are optimal for high availability and cost efficiency.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCNE question test?
Designing, planning, and prototyping a GCP network — This question tests Designing, planning, and prototyping a GCP network — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a Cloud NAT gateway in each zone and configure region-specific NAT rules. — A Cloud NAT gateway per zone provides highly available outbound connectivity for instances without external IPs. By placing a gateway in each zone, traffic from instances in that zone uses the local gateway, avoiding cross-zone hops and ensuring automatic failover if a zone fails. This meets the cost-effective and no-manual-failover requirements without needing instance-level external IPs.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 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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