- A
The health check is using the HTTP protocol instead of TCP.
Why wrong: The health check is explicitly configured as TCP, so using HTTP would not cause failure; it would simply work differently.
- B
The MIG's autohealing policy is set to a too-aggressive initial delay.
Why wrong: Autohealing policy affects how quickly instances are recreated, but it does not cause health check failures.
- C
The firewall rule allowing health check probes is not applied to the instances due to missing network tags.
Health check probes will be blocked if the firewall rule does not apply to the instances' network tags, even if the rule exists.
- D
The application is only listening on the localhost interface.
Why wrong: The verification shows the application listens on 0.0.0.0:8080, so it responds on all interfaces.
Google ACE Practice Question: Ensuring successful operation of a cloud solution
This ACE practice question tests your understanding of ensuring successful operation of a cloud solution. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
Your company runs a stateful web application on a managed instance group (MIG) in us-central1 across three zones. The application uses a TCP health check on port 8080. Recently, instances have been recreated frequently due to health check failures, though the application logs show no errors and instances are accessible via SSH. The firewall rules allow traffic from the health check ranges (130.211.0.0/22 and 35.191.0.0/16) to port 8080. You have verified that the application is listening on 0.0.0.0:8080. Which of the following is the most likely cause of the health check failures?
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 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 firewall rule allowing health check probes is not applied to the instances due to missing network tags.
Since the application listens on 0.0.0.0, it should respond on all interfaces, but if the firewall is not properly configured for the health check source ranges, probes could be blocked. The firewall rule exists but might not be applied to the correct network tags or target instances. Option B is the most common cause of health check failures in such scenarios. Option A (wrong protocol) is incorrect because TCP health check uses TCP. Option C (autohealing misconfiguration) would affect behavior but not cause failures. Option D (app listening on wrong interface) is ruled out by listening on 0.0.0.0.
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.
- ✗
The health check is using the HTTP protocol instead of TCP.
- ✗
The MIG's autohealing policy is set to a too-aggressive initial delay.
Why it's wrong here
Autohealing policy affects how quickly instances are recreated, but it does not cause health check failures.
- ✓
The firewall rule allowing health check probes is not applied to the instances due to missing network tags.
Why this is correct
Health check probes will be blocked if the firewall rule does not apply to the instances' network tags, even if the rule exists.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The application is only listening on the localhost interface.
Why it's wrong here
The verification shows the application listens on 0.0.0.0:8080, so it responds on all interfaces.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
The verification shows the application listens on 0.0.0.0:8080, so it responds on all interfaces.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 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.
Identify which ACE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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Ensuring successful operation of a cloud solution — study guide chapter
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FAQ
Questions learners often ask
What does this ACE question test?
Ensuring successful operation of a cloud solution — This question tests Ensuring successful operation of a cloud solution — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The firewall rule allowing health check probes is not applied to the instances due to missing network tags. — Since the application listens on 0.0.0.0, it should respond on all interfaces, but if the firewall is not properly configured for the health check source ranges, probes could be blocked. The firewall rule exists but might not be applied to the correct network tags or target instances. Option B is the most common cause of health check failures in such scenarios. Option A (wrong protocol) is incorrect because TCP health check uses TCP. Option C (autohealing misconfiguration) would affect behavior but not cause failures. Option D (app listening on wrong interface) is ruled out by listening on 0.0.0.0.
What should I do if I get this ACE question wrong?
Identify which ACE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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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