- A
Enable Private Google Access on subnets that host instances without external IP addresses.
This allows instances to access Google APIs over the internal network, reducing exposure to the internet.
- B
Configure firewall rules with stateful packet inspection disabled to maximize throughput.
Why wrong: Firewall rules are stateful by default; disabling stateful inspection would break return traffic and is not a security best practice.
- C
Use VPC Service Controls to create a perimeter around the sensitive data stored in Cloud Storage and BigQuery.
VPC Service Controls help prevent data exfiltration by controlling access to Google Cloud services.
- D
Use VPC Network Peering to isolate the sensitive workloads from other projects.
Why wrong: VPC peering is for connectivity, not security isolation; it does not provide access controls.
- E
Create a Cloud NAT gateway to filter inbound traffic from the internet.
Why wrong: Cloud NAT is used for outbound traffic from instances without external IPs, not for inbound filtering.
Quick Answer
The answer is to use VPC Service Controls to create a security perimeter around sensitive data in Cloud Storage and BigQuery, and to enable Private Google Access for VM instances with only internal IPs. VPC Service Controls prevent data exfiltration by restricting access to managed services from outside a defined perimeter, while Private Google Access allows instances without external IPs to reach Google APIs through Google’s internal network, reducing the attack surface. On the Google Professional Cloud Network Engineer exam, this pairing tests your understanding of layered network security—defense-in-depth—where you must combine data-centric controls with network-level isolation. A common trap is choosing Cloud NAT or VPNs, which handle outbound connectivity but do not prevent data exfiltration or enforce perimeters. Remember the mnemonic: “Private for paths, Perimeter for protection”—Private Google Access secures the traffic path, while VPC Service Controls lock down the data boundary.
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 financial services company is migrating sensitive workloads to Google Cloud. They need to implement a defense-in-depth strategy to protect their VPC networks. Which TWO actions should they take to meet their security requirements? (Choose two.)
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
Enable Private Google Access on subnets that host instances without external IP addresses.
Option A is correct because Private Google Access allows VM instances that have only internal IP addresses (no external IPs) to reach Google APIs and services (e.g., Cloud Storage, BigQuery) through the Google Cloud network. This eliminates the need for an external IP address, reducing the attack surface and supporting a defense-in-depth strategy by keeping traffic within Google's internal infrastructure.
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.
- ✓
Enable Private Google Access on subnets that host instances without external IP addresses.
Why this is correct
This allows instances to access Google APIs over the internal network, reducing exposure to the internet.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Configure firewall rules with stateful packet inspection disabled to maximize throughput.
Why it's wrong here
Firewall rules are stateful by default; disabling stateful inspection would break return traffic and is not a security best practice.
- ✓
Use VPC Service Controls to create a perimeter around the sensitive data stored in Cloud Storage and BigQuery.
Why this is correct
VPC Service Controls help prevent data exfiltration by controlling access to Google Cloud services.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use VPC Network Peering to isolate the sensitive workloads from other projects.
Why it's wrong here
VPC peering is for connectivity, not security isolation; it does not provide access controls.
- ✗
Create a Cloud NAT gateway to filter inbound traffic from the internet.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that Cloud NAT can filter inbound traffic, but Cloud NAT is strictly an outbound proxy that does not inspect or filter inbound connections; inbound traffic must be controlled by firewall rules or Cloud Armor.
Detailed technical explanation
How to think about this question
Private Google Access works by using the default internet gateway's next-hop for the IP range 199.36.153.4/30 (Google's restricted VIP) and 199.36.153.8/30 (Google's private VIP) for API access, routing traffic through the VPC's internal network without needing an external IP. VPC Service Controls enforce a perimeter by using context-aware access policies that block data exfiltration from services like Cloud Storage and BigQuery, even if the request originates from within the same VPC or from an authorized identity. Under the hood, VPC Service Controls leverage IAM conditions and access levels to create a dry-run or enforced perimeter that prevents unauthorized copying or movement of data outside the defined boundary.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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?
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: Enable Private Google Access on subnets that host instances without external IP addresses. — Option A is correct because Private Google Access allows VM instances that have only internal IP addresses (no external IPs) to reach Google APIs and services (e.g., Cloud Storage, BigQuery) through the Google Cloud network. This eliminates the need for an external IP address, reducing the attack surface and supporting a defense-in-depth strategy by keeping traffic within Google's internal infrastructure.
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 30, 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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