The correct statements about Cloud NAT are that it supports both TCP and UDP protocols, requires a default route (0.0.0.0/0) to the internet gateway, and can be configured with a manual list of NAT IP addresses. Cloud NAT functions as a regional resource that performs source network address translation for private instances lacking external IP addresses, allowing them to initiate outbound connections to the internet while remaining unreachable from outside. On the Google Professional Cloud Network Engineer exam, this topic tests your understanding of how Cloud NAT differs from assigning external IPs directly—a common trap is confusing its regional scope with a per-subnet scope, or assuming it assigns external IPs to instances. Remember that Cloud NAT is regional, not per-subnet, and it never assigns external IPs; it only translates outbound traffic for instances without them. A useful memory tip is “NAT is regional, not individual,” reinforcing that it operates at the region level and applies to all configured subnets within that region.
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.
An organization is configuring Cloud NAT to allow private instances to access the internet. Which three statements about Cloud NAT are correct? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cloud NAT requires that the VPC has a default route (0.0.0.0/0) to the internet gateway.
Options A, C, and D are correct. Option A: Cloud NAT supports both TCP and UDP. Option C: Cloud NAT requires a default route (0.0.0.0/0) to the internet gateway to function. Option D: Cloud NAT can be configured with a manual list of NAT IP addresses. Option B is incorrect because Cloud NAT provides NAT for instances without external IPs; it does not assign external IPs to instances. Option E is incorrect because Cloud NAT is regional, not per subnet; it applies to all subnets in the region that are configured to use it.
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 can be configured per subnet or per region.
Why it's wrong here
Cloud NAT is regional; you specify which subnets use it, but it is not per subnet.
✓
Cloud NAT requires that the VPC has a default route (0.0.0.0/0) to the internet gateway.
Why this is correct
Without a default route, traffic cannot reach 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: Cloud NAT requires that the VPC has a default route (0.0.0.0/0) to the internet gateway. — Options A, C, and D are correct. Option A: Cloud NAT supports both TCP and UDP. Option C: Cloud NAT requires a default route (0.0.0.0/0) to the internet gateway to function. Option D: Cloud NAT can be configured with a manual list of NAT IP addresses. Option B is incorrect because Cloud NAT provides NAT for instances without external IPs; it does not assign external IPs to instances. Option E is incorrect because Cloud NAT is regional, not per subnet; it applies to all subnets in the region that are configured to use it.
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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses Cloud NAT to allow instances without external IPs to access the internet. They have a managed instance group (MIG) in us-central1 with 10 instances, all using the same Cloud NAT configured with a single NAT IP address. They notice that some instances are unable to connect to a specific external API endpoint, while others can. The error on the failing instances is 'Cannot connect to host'. The NAT IP is not blacklisted by the API. The Cloud NAT gateway has default settings with a minimum port per VM of 64 and a maximum of 65536. What is the most likely cause?
medium
A.The instances are using different service accounts, and the NAT is not configured to allow all.
B.The Cloud NAT's idle timeout is set too low, causing connections to be dropped.
C.The external API endpoint has a rate limit that is being hit by the NAT IP.
✓ D.Port exhaustion is occurring; increase the number of NAT IPs or increase the minimum ports per VM.
Why D: Cloud NAT uses source network address translation (SNAT) and maps internal IPs to the NAT IP using ports. By default, Cloud NAT allocates a range of ports per VM. If the instances are making many connections, they may exhaust the allocated ports. The symptom that only some instances fail suggests that the failing instances may have run out of ephemeral ports. Option D is correct: Increase the number of NAT IP addresses or increase the minimum ports per VM.
Variation 2. Refer to the exhibit. Instances in subnet-b cannot access the internet through Cloud NAT. What is the most likely reason?
easy
A.The firewall rules in subnet-b block egress.
B.The NAT IP address pool is exhausted.
C.Subnet-b has overlapping subnets.
✓ D.Subnet-b is not included in the Cloud NAT configuration.
Why D: The Cloud NAT configuration only includes subnet-a, so subnet-b is not NATed.
Variation 3. Drag and drop the steps to configure a Cloud NAT for private instances to access the internet into the correct order.
medium
Why : Cloud NAT requires a Cloud Router first. Then create NAT, assign IPs, and apply to subnets. Testing confirms internet access.
Variation 4. A company wants to provide internet access to their Compute Engine instances without assigning external IP addresses. Which Google Cloud service should they use?
easy
✓ A.Cloud NAT
B.Cloud VPN
C.Private Google Access
D.VPC Peering
Why A: Cloud NAT allows instances without external IPs to access the internet. Other options are for different purposes.
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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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