- A
A VPC firewall rule with a deny ingress for that IP
Why wrong: VPC firewall rules apply to VM instances, not load balancers.
- B
A custom rule with a 'deny' action and the IP address in the 'src_ip_ranges' field
Custom rules can block specific IPs using 'src_ip_ranges'.
- C
A Cloud Armor rate limiting rule
Why wrong: Rate limiting restricts request rate, not absolute block.
- D
A preconfigured rule from the OWASP ModSecurity CRS
Why wrong: Preconfigured rules target attack patterns, not specific IPs.
Question 183 of 1,000
PCSE Configuring Network Security Practice Question
This PCSE practice question tests your understanding of configuring network security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 needs to block a specific IP address from accessing an HTTPS load balancer. Which Cloud Armor rule should be used?
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
✓
A custom rule with a 'deny' action and the IP address in the 'src_ip_ranges' field
Cloud Armor custom rules allow IP allow/deny lists. A deny rule with the specific IP address will block traffic.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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 VPC firewall rule with a deny ingress for that IP
- ✓
A custom rule with a 'deny' action and the IP address in the 'src_ip_ranges' field
Why this is correct
Custom rules can block specific IPs using 'src_ip_ranges'.
Related concept
Standard ACLs match source addresses.
- ✗
A Cloud Armor rate limiting rule
Why it's wrong here
Rate limiting restricts request rate, not absolute block.
- ✗
A preconfigured rule from the OWASP ModSecurity CRS
Why it's wrong here
Preconfigured rules target attack patterns, not specific IPs.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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 ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related PCSE ACL questions on filtering logic and placement.
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Configuring Network Security — study guide chapter
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FAQ
Questions learners often ask
What does this PCSE question test?
Configuring Network Security — This question tests Configuring Network Security — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: A custom rule with a 'deny' action and the IP address in the 'src_ip_ranges' field — Cloud Armor custom rules allow IP allow/deny lists. A deny rule with the specific IP address will block traffic.
What should I do if I get this PCSE question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related PCSE ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Last reviewed: Jul 4, 2026
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