The correct answer is that no additional configuration is required beyond creating the subnet. This is because a public load balancer in Google Cloud uses internal VPC routing to forward traffic to backend instances, even when those instances lack external IPs. The load balancer’s envoy proxies reside within the VPC and communicate with backends over private IP addresses, so no NAT gateway, Private Google Access, or default route is needed. On the Google Professional Cloud Network Engineer exam, this concept tests your understanding of how load balancers decouple frontend and backend networking—a common trap is assuming private backends need outbound internet access or special routes. Remember: the load balancer is the endpoint; the backend only needs to be reachable within the VPC. A useful memory tip is “LB is the bridge, not the boat”—the load balancer handles public ingress, while backends stay private and require no extra configuration.
PCNE Implementing a Virtual Private Cloud Practice Question
This PCNE practice question tests your understanding of implementing a virtual private cloud. 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 wants to deploy a web application with a public-facing load balancer and a private backend. The backend instances must not have external IPs. Which statement about the VPC configuration is correct?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
No additional configuration is required beyond creating the subnet.
Option D is correct because instances without external IPs can still receive traffic from a public load balancer. No additional configuration such as NAT or Private Google Access is needed for this purpose. Option A is incorrect because Private Google Access is for accessing Google APIs, not for load balancer traffic. Option B is incorrect because Cloud NAT provides outbound internet access, which is not required. Option C is incorrect because the backend subnet does not need a default route; traffic from the load balancer comes through the VPC internal routing.
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.
✗
Cloud NAT must be configured for the backend subnet.
Why it's wrong here
Cloud NAT is for outbound internet access, not required here.
✗
The backend subnet must have a default route to the internet.
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.
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.
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.
Implementing a Virtual Private Cloud — This question tests Implementing a Virtual Private Cloud — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: No additional configuration is required beyond creating the subnet. — Option D is correct because instances without external IPs can still receive traffic from a public load balancer. No additional configuration such as NAT or Private Google Access is needed for this purpose. Option A is incorrect because Private Google Access is for accessing Google APIs, not for load balancer traffic. Option B is incorrect because Cloud NAT provides outbound internet access, which is not required. Option C is incorrect because the backend subnet does not need a default route; traffic from the load balancer comes through the VPC internal routing.
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.
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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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