The answer is that the bucket allows public read access via allUsers in both ACL and legacy role, which is the most significant security issue. This is because the command output reveals two independent mechanisms granting public access: an ACL entry giving allUsers READER permission, and a legacy bucket role roles/storage.legacyBucketReader assigned to allUsers, meaning any object in the bucket is readable by anyone on the internet without authentication. On the Google Professional Cloud Security Engineer exam, this scenario tests your ability to identify overlapping public access controls, a common trap where candidates overlook legacy roles when ACLs are present. The key insight is that Cloud Storage permissions can accumulate—removing one public access method does not secure the bucket if another remains. Memory tip: think “double doors” for allUsers—both ACL and legacy role must be locked to prevent public exposure.
PCSE Ensuring data protection Practice Question
This PCSE practice question tests your understanding of ensuring data protection. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The bucket allows public read access via 'allUsers' in both ACL and legacy role.
Option C is correct because the command output shows that the bucket has both an ACL granting 'allUsers' READER access and a legacy bucket role 'roles/storage.legacyBucketReader' assigned to 'allUsers'. This means the bucket is publicly readable via two independent mechanisms, which is the most significant security issue as it exposes all objects to the internet without authentication.
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 domain example.com has viewer access, which may be too broad.
Why it's wrong here
Domain access is a lesser issue than public access.
✗
The legacy role 'roles/storage.legacyBucketReader' is used.
Why it's wrong here
Legacy role is acceptable; the problem is allUsers.
✓
The bucket allows public read access via 'allUsers' in both ACL and legacy role.
Why this is correct
AllUsers gives access to anyone on the internet.
Related concept
Read the scenario before looking for a memorised answer.
✗
Uniform bucket-level access is disabled, allowing ACLs.
Why it's wrong here
While a risk, public access via allUsers is more immediate.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the distinction between a legacy role being used (which is not inherently insecure) versus that role being granted to 'allUsers' (which creates public access), causing candidates to incorrectly select Option B because they focus on the role name rather than the principal it is assigned to.
Detailed technical explanation
How to think about this question
Under the hood, Cloud Storage evaluates access by first checking uniform bucket-level access; if disabled, it checks ACLs and then IAM policies. The legacy bucket role 'roles/storage.legacyBucketReader' grants 'storage.buckets.get' and 'storage.objects.list' permissions, which when combined with 'allUsers' allows anyone to list all objects in the bucket. In a real-world scenario, this could lead to data exfiltration if the bucket contains sensitive files, as attackers can enumerate and download objects without any authentication.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Ensuring data protection — This question tests Ensuring data protection — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The bucket allows public read access via 'allUsers' in both ACL and legacy role. — Option C is correct because the command output shows that the bucket has both an ACL granting 'allUsers' READER access and a legacy bucket role 'roles/storage.legacyBucketReader' assigned to 'allUsers'. This means the bucket is publicly readable via two independent mechanisms, which is the most significant security issue as it exposes all objects to the internet without authentication.
What should I do if I get this PCSE 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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Question Discussion
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