- A
Set up Cloud NAT to provide outbound internet access for the instances.
Why wrong: Cloud NAT is for outbound traffic, not inbound security.
- B
Configure VPC firewall rules on the subnet to allow only the IP ranges.
Why wrong: Cloud Armor operates at the load balancer; VPC firewall rules at the instance level are redundant.
- C
Enable predefined WAF rules (e.g., OWASP Top 10) in the Cloud Armor security policy.
WAF rules block common web attacks like SQL injection and XSS.
- D
Create a Cloud Armor security policy with an allow rule for the IP ranges and a default deny rule for all other traffic.
This restricts inbound traffic to the specified IP ranges at the load balancer.
- E
Enable Cloud CDN to cache static content from the backend.
Why wrong: Cloud CDN improves content delivery but does not restrict traffic or block attacks.
Google ACE Configuring access and security Practice Question
This ACE practice question tests your understanding of configuring access and security. 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.
A company uses Cloud Armor to protect an HTTP Load Balancer. They want to allow traffic only from specific IP ranges (198.51.100.0/24 and 203.0.113.0/24) and block common web attacks like SQL injection and XSS. Which TWO actions should they take?
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
Enable predefined WAF rules (e.g., OWASP Top 10) in the Cloud Armor security policy.
Option A creates a security policy with an allow rule for the IP ranges and a deny rule for all other traffic, which is necessary to restrict access. Option C enables WAF rules in Cloud Armor, which blocks common web attacks. Option B (Cloud CDN caching) does not affect access control. Option D (VPC firewall rules at instance level) is not relevant because Cloud Armor works at the load balancer. Option E (Cloud NAT) is for outbound traffic, not inbound security.
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.
- ✗
Set up Cloud NAT to provide outbound internet access for the instances.
Why it's wrong here
Cloud NAT is for outbound traffic, not inbound security.
- ✗
Configure VPC firewall rules on the subnet to allow only the IP ranges.
Why it's wrong here
Cloud Armor operates at the load balancer; VPC firewall rules at the instance level are redundant.
- ✓
Enable predefined WAF rules (e.g., OWASP Top 10) in the Cloud Armor security policy.
Why this is correct
WAF rules block common web attacks like SQL injection and XSS.
Related concept
CIDR notation defines the prefix length.
- ✓
Create a Cloud Armor security policy with an allow rule for the IP ranges and a default deny rule for all other traffic.
Why this is correct
This restricts inbound traffic to the specified IP ranges at the load balancer.
Related concept
CIDR notation defines the prefix length.
- ✗
Enable Cloud CDN to cache static content from the backend.
Why it's wrong here
Cloud CDN improves content delivery but does not restrict traffic or block attacks.
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.
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 ACE subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Questions learners often ask
What does this ACE question test?
Configuring access and security — This question tests Configuring access and security — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Enable predefined WAF rules (e.g., OWASP Top 10) in the Cloud Armor security policy. — Option A creates a security policy with an allow rule for the IP ranges and a deny rule for all other traffic, which is necessary to restrict access. Option C enables WAF rules in Cloud Armor, which blocks common web attacks. Option B (Cloud CDN caching) does not affect access control. Option D (VPC firewall rules at instance level) is not relevant because Cloud Armor works at the load balancer. Option E (Cloud NAT) is for outbound traffic, not inbound security.
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.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
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Last reviewed: Jun 23, 2026
This ACE 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 ACE exam.
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