- A
Configure a proxy instance with an external IP and route traffic through it
Why wrong: This requires additional management and does not preserve the original source IP as seen by the SaaS (it would show the proxy's IP unless configured otherwise).
- B
Use Cloud NAT with a static NAT IP
Cloud NAT provides outbound internet access for VMs without external IPs. Using a static NAT IP preserves source IP and provides consistent IP for whitelisting.
- C
Assign external IPs to each VM
Why wrong: This would give VMs external IPs, which contradicts the requirement of no external IPs.
- D
Use Private Google Access
Why wrong: Private Google Access only works for Google APIs, not for third-party SaaS on the internet.
Question 46 of 1,000
PCNE Implementing VPC Instances Practice Question
This PCNE practice question tests your understanding of implementing vpc instances. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 an application running on Compute Engine that needs to send traffic to a third-party SaaS service on the internet. The VMs have no external IPs. Which solution provides outbound connectivity with minimal configuration and allows source IP preservation?
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
✓
Use Cloud NAT with a static NAT IP
Cloud NAT allows VMs without external IPs to reach the internet. It preserves the source IP (the NAT IP) for outbound connections. It is regional and can be configured per subnet.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure a proxy instance with an external IP and route traffic through it
Why it's wrong here
This requires additional management and does not preserve the original source IP as seen by the SaaS (it would show the proxy's IP unless configured otherwise).
- ✓
Use Cloud NAT with a static NAT IP
- ✗
Assign external IPs to each VM
Why it's wrong here
This would give VMs external IPs, which contradicts the requirement of no external IPs.
- ✗
Use Private Google Access
Why it's wrong here
Private Google Access only works for Google APIs, not for third-party SaaS on the internet.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Trap categories for this question
Command / output trap
This requires additional management and does not preserve the original source IP as seen by the SaaS (it would show the proxy's IP unless configured otherwise).
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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.
Visual reference
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCNE subnetting questions on CIDR, address ranges, and subnet selection.
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Implementing VPC Instances — study guide chapter
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FAQ
Questions learners often ask
What does this PCNE question test?
Implementing VPC Instances — This question tests Implementing VPC Instances — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Use Cloud NAT with a static NAT IP — Cloud NAT allows VMs without external IPs to reach the internet. It preserves the source IP (the NAT IP) for outbound connections. It is regional and can be configured per subnet.
What should I do if I get this PCNE question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCNE subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
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Last reviewed: Jul 4, 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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