- A
The traffic is allowed because allow rules override deny rules
Why wrong: In GCP, deny rules can override allow rules if priority is higher.
- B
The traffic is allowed because the allow rule covers a broader range
Why wrong: Priority determines which rule applies, not specificity.
- C
The traffic is denied only if the instance has a tag matching the deny rule
Why wrong: The deny rule does not specify tags; it applies to all instances.
- D
The traffic is denied because the deny rule has higher priority
Correct. The deny rule (priority 500) has higher priority than the allow rule (priority 1000).
Question 287 of 1,000
PCNE Implementing VPC Instances Practice Question
This PCNE practice question tests your understanding of implementing vpc instances. 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 engineer has configured a firewall rule with priority 1000 that allows ingress traffic on TCP port 443 from source IP range 10.0.0.0/8. Another rule with priority 500 denies ingress on TCP port 443 from source IP 10.0.1.0/24. What will happen to traffic from 10.0.1.5 destined to the instance on port 443?
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
✓
The traffic is denied because the deny rule has higher priority
Firewall rules are evaluated by priority (lower number = higher priority). Rule with priority 500 (deny) takes precedence over priority 1000 (allow). So traffic from 10.0.1.5 is denied.
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.
- ✗
The traffic is allowed because allow rules override deny rules
Why it's wrong here
In GCP, deny rules can override allow rules if priority is higher.
- ✗
The traffic is allowed because the allow rule covers a broader range
Why it's wrong here
Priority determines which rule applies, not specificity.
- ✗
The traffic is denied only if the instance has a tag matching the deny rule
Why it's wrong here
The deny rule does not specify tags; it applies to all instances.
- ✓
The traffic is denied because the deny rule has higher priority
Why this is correct
Correct. The deny rule (priority 500) has higher priority than the allow rule (priority 1000).
Related concept
Standard ACLs match source addresses.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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 PCNE ACL questions on filtering logic and placement.
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FAQ
Questions learners often ask
What does this PCNE question test?
Implementing VPC Instances — This question tests Implementing VPC Instances — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The traffic is denied because the deny rule has higher priority — Firewall rules are evaluated by priority (lower number = higher priority). Rule with priority 500 (deny) takes precedence over priority 1000 (allow). So traffic from 10.0.1.5 is denied.
What should I do if I get this PCNE 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 PCNE 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
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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