- A
Only SSH from the corporate range is allowed — the more specific rule takes precedence for all traffic
Why wrong: Firewall rules are not mutually exclusive in GCP — all matching allow rules apply. The priority 999 SSH rule doesn't block the priority 1000 allow-all rule from matching other traffic.
- B
SSH from corporate IP plus all traffic from all IPs — both allow rules match for their respective traffic
GCP evaluates firewall rules independently. Priority 999 allows corporate SSH. Priority 1000 allows everything else. The allow-all rule represents a critical security vulnerability.
- C
No traffic is allowed — deny rules override allow rules in GCP
Why wrong: There are no deny rules in this scenario — both rules are allow rules. GCP's implied deny only applies when no allow rule matches.
- D
All traffic from all IPs is allowed — the priority 1000 allow-all overrides the more specific priority 999 rule
Why wrong: Priority 999 (lower number) takes precedence over priority 1000 — but both allow rules match independently for their respective traffic.
Quick Answer
The answer is that both allow rules match and apply, so SSH from the corporate IP and all other traffic from all IPs are allowed. This is correct because Google Cloud VPC firewall rules evaluate each allow rule independently; when two allow rules match a packet, the combined effect is that all permitted traffic is allowed, regardless of priority. Unlike deny rules, which are evaluated by the lowest priority number first, allow rules do not override each other—they simply add permissions. On the Google Associate Cloud Engineer exam, this concept tests your understanding that firewall rules allow both match priority does not create a conflict; the common trap is assuming a higher-priority allow rule blocks a lower-priority one, but only explicit deny rules can deny traffic. Remember the memory tip: “Allow rules stack, deny rules block”—so when you see two allow rules, think additive, not exclusive.
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 developer accidentally creates a firewall rule allowing all inbound traffic (0.0.0.0/0) on all ports to all instances in a production VPC. The rule has priority 1000. The team has an existing rule allowing only SSH (port 22) from the corporate IP range at priority 999. Which traffic is actually allowed?
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
SSH from corporate IP plus all traffic from all IPs — both allow rules match for their respective traffic
In Google Cloud VPC firewall rules, both allow rules are evaluated independently. The rule at priority 999 allows SSH (TCP port 22) from the corporate IP range, and the rule at priority 1000 allows all traffic from all IPs (0.0.0.0/0) on all ports. Since both rules are allow rules and match the traffic, the result is that SSH traffic from the corporate IP is allowed by the more specific rule, and all other traffic (including SSH from other IPs and all other protocols) is allowed by the broader rule. There is no implicit deny in GCP firewall rules; only explicit deny rules can block traffic, and no deny rule is present here.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Only SSH from the corporate range is allowed — the more specific rule takes precedence for all traffic
- ✓
SSH from corporate IP plus all traffic from all IPs — both allow rules match for their respective traffic
- ✗
No traffic is allowed — deny rules override allow rules in GCP
Why it's wrong here
There are no deny rules in this scenario — both rules are allow rules. GCP's implied deny only applies when no allow rule matches.
- ✗
All traffic from all IPs is allowed — the priority 1000 allow-all overrides the more specific priority 999 rule
Why it's wrong here
Priority 999 (lower number) takes precedence over priority 1000 — but both allow rules match independently for their respective traffic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that a higher-priority (lower number) rule always overrides a lower-priority rule, but in GCP, this only applies when comparing allow vs. deny rules, not between two allow rules.
Trap categories for this question
Scenario analysis trap
There are no deny rules in this scenario — both rules are allow rules. GCP's implied deny only applies when no allow rule matches.
Detailed technical explanation
How to think about this question
GCP firewall rules are stateful and evaluated in priority order (lower number = higher priority), but only when there is a conflict between an allow and a deny rule does priority decide which wins. If multiple allow rules match, all matching allow rules are applied, effectively granting the union of their permissions. This behavior differs from AWS security groups, which have an implicit deny-all at the end, and from Azure NSGs, which use a priority-based allow/deny system where the highest priority rule wins. In practice, this means that accidentally creating a low-priority allow-all rule will not be blocked by a higher-priority specific allow rule; it will open all traffic unless a deny rule explicitly blocks it.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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 — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: SSH from corporate IP plus all traffic from all IPs — both allow rules match for their respective traffic — In Google Cloud VPC firewall rules, both allow rules are evaluated independently. The rule at priority 999 allows SSH (TCP port 22) from the corporate IP range, and the rule at priority 1000 allows all traffic from all IPs (0.0.0.0/0) on all ports. Since both rules are allow rules and match the traffic, the result is that SSH traffic from the corporate IP is allowed by the more specific rule, and all other traffic (including SSH from other IPs and all other protocols) is allowed by the broader rule. There is no implicit deny in GCP firewall rules; only explicit deny rules can block traffic, and no deny rule is present here.
What should I do if I get this ACE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 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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