- A
Zero NICs: use an internal load balancer
Why wrong: A VM must have at least one NIC to be functional. An internal load balancer can distribute traffic to VMs but does not replace the VM's network interface.
- B
One NIC, with IP forwarding enabled
Why wrong: A single NIC can forward traffic but does not provide separation between management and data planes, which is a best practice for network appliances.
- C
Two NICs: one for management, one for data traffic
Multiple NICs allow separation of management and data traffic. The management NIC can be used for SSH/API access, while data NICs handle forwarded traffic.
- D
Three NICs: one for each subnet it routes between
Why wrong: While possible, the minimum and typical setup is two NICs. Subnets can be reached via routes, so separate NIC per subnet is not necessary.
PCNE Implementing VPC Instances Practice Question
This PCNE practice question tests your understanding of implementing vpc instances. 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.
An engineer is deploying a network appliance (e.g., a firewall) in a VPC. The appliance needs to handle traffic between different subnets. How many network interfaces should the appliance VM have, and why?
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
Two NICs: one for management, one for data traffic
Network appliances often use multiple NICs for traffic segregation: one for management, others for data traffic. Each NIC can be in a different subnet. NIC0 is the primary and must be connected. Up to 8 NICs are supported.
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.
- ✗
Zero NICs: use an internal load balancer
Why it's wrong here
A VM must have at least one NIC to be functional. An internal load balancer can distribute traffic to VMs but does not replace the VM's network interface.
- ✗
One NIC, with IP forwarding enabled
Why it's wrong here
A single NIC can forward traffic but does not provide separation between management and data planes, which is a best practice for network appliances.
- ✓
Two NICs: one for management, one for data traffic
- ✗
Three NICs: one for each subnet it routes between
Why it's wrong here
While possible, the minimum and typical setup is two NICs. Subnets can be reached via routes, so separate NIC per subnet is not necessary.
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.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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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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: Two NICs: one for management, one for data traffic — Network appliances often use multiple NICs for traffic segregation: one for management, others for data traffic. Each NIC can be in a different subnet. NIC0 is the primary and must be connected. Up to 8 NICs are supported.
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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