The answer is that the load balancer forwarding rule must be in the same region as the backend instances, and the backend service must reference a health check. These two requirements are fundamental because an internal TCP/UDP load balancer operates regionally, not globally, so the forwarding rule and its backend VMs must reside within the same regional scope to route traffic correctly. The health check is mandatory to determine instance health and ensure traffic is only sent to responsive backends. On the Google Professional Cloud Network Engineer exam, this question tests your understanding of shared VPC constraints, where a common trap is assuming the load balancer needs an IP from the host project or that global routing applies. Remember that ILB is strictly regional, and unlike HTTP load balancers, it does not use proxy subnets. A useful memory tip: think "same region, healthy backends" — the forwarding rule and health check are the two non-negotiable pillars for any internal TCP/UDP load balancer in a shared VPC.
PCNE Configuring network services Practice Question
This PCNE practice question tests your understanding of configuring network services. 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.
Which TWO of the following are required when setting up an internal TCP/UDP load balancer (ILB) in a shared VPC environment?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A health check must be configured for the backend service.
Correct answers: A (The load balancer must be in the same region as the backend instances) and C (The backend service must reference a health check). Option B is wrong because ILB does not require an internal IP address from the host project; it can use an IP from the service project's subnet. Option D is wrong because ILB does not require global routing; it works within a region. Option E is wrong because the firewall rule for health checks must allow traffic from the health check ranges, not from the proxy subnet (ILB does not use proxy subnets like in HTTP LB).
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.
✓
A health check must be configured for the backend service.
Why this is correct
Health checks are required to determine instance health.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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.
Configuring network services — This question tests Configuring network services — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: A health check must be configured for the backend service. — Correct answers: A (The load balancer must be in the same region as the backend instances) and C (The backend service must reference a health check). Option B is wrong because ILB does not require an internal IP address from the host project; it can use an IP from the service project's subnet. Option D is wrong because ILB does not require global routing; it works within a region. Option E is wrong because the firewall rule for health checks must allow traffic from the health check ranges, not from the proxy subnet (ILB does not use proxy subnets like in HTTP LB).
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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Question Discussion
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