Google ACE Planning and configuring a cloud solution Practice Question
This ACE practice question tests your understanding of planning and configuring a cloud solution. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 a Compute Engine instance in the us-west1 region that does not have a public IP address. The instance is part of a VPC network that has a Cloud NAT gateway configured in the us-east1 region. The Cloud NAT gateway is configured to allow all traffic from the VPC subnet. The VPC has a default route (0.0.0.0/0) pointing to the default internet gateway. Firewall rules allow all egress traffic. The instance is unable to download updates from the internet. What is the most likely cause of this problem?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Cloud NAT gateway is in a different region than the instance.
Cloud NAT is regional. An instance in us-west1 cannot use a Cloud NAT gateway in us-east1 because NAT is only applied to instances in the same region. The instance's traffic destined for the internet is not translated, so it cannot reach external hosts without a public IP.
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.
✗
The instance's firewall rules block egress traffic to port 80.
Why it's wrong here
Incorrect. The stem states that firewall rules allow all egress traffic.
✓
The Cloud NAT gateway is in a different region than the instance.
Why this is correct
Correct. Cloud NAT is region-scoped; instances can only use NAT gateways in the same region.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
The instance's service account does not have the compute.instances.update permission.
Why it's wrong here
Incorrect. The service account permissions are not required for internet access via Cloud NAT.
✗
The VPC does not have a route for the instance's subnet to the internet gateway.
Why it's wrong here
Incorrect. The VPC has a default route to the internet gateway, which is necessary but not sufficient without a NAT in the same region.
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
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this ACE question in full detail.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ACE subnetting questions on CIDR, address ranges, and subnet selection.
Planning and configuring a cloud solution — This question tests Planning and configuring a cloud solution — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The Cloud NAT gateway is in a different region than the instance. — Cloud NAT is regional. An instance in us-west1 cannot use a Cloud NAT gateway in us-east1 because NAT is only applied to instances in the same region. The instance's traffic destined for the internet is not translated, so it cannot reach external hosts without a public IP.
What should I do if I get this ACE 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 ACE subnetting questions on CIDR, address ranges, and subnet selection.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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