The answer is to modify the bucket policy to remove the Allow effect for Principal "*" and to remove the public access grant from the bucket ACL. This is correct because S3 has two independent access control mechanisms: bucket policies and Access Control Lists (ACLs). Even if you fix the policy, a separate ACL that grants public read access can still leave the bucket exposed, so both must be addressed to fully remediate a publicly accessible S3 bucket. On the AWS Certified Developer Associate DVA-C02 exam, this question tests your understanding of the layered security model for S3, where blocking public access requires checking both the policy and the ACL. A common trap is assuming that modifying only the bucket policy is sufficient, but the ACL is a separate vector for anonymous access. Remember the memory tip: "Policy and ACL, both must be well" — always verify both settings to ensure no public access remains.
DVA-C02 Security Practice Question
This DVA-C02 practice question tests your understanding of security. 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.
A security audit reveals that an S3 bucket is publicly accessible. The bucket policy is as follows: {"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":"*","Action":"s3:GetObject","Resource":"arn:aws:s3:::my-bucket/*"}]}. Which TWO actions should be taken to remediate this issue? (Select TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Remove the public access grant from the bucket ACL.
Option A is correct because the bucket ACL may still grant public access even if the bucket policy is the primary issue. Removing the public access grant from the ACL ensures that no anonymous principals have s3:GetObject permissions via ACLs, which is a separate access control mechanism from bucket policies. This is a direct remediation step to eliminate public read access.
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.
✓
Remove the public access grant from the bucket ACL.
Read the scenario before looking for a memorised answer.
✗
Create an IAM user policy that denies s3:GetObject for anonymous users.
Why it's wrong here
IAM policies do not apply to anonymous users.
✗
Enable versioning on the bucket.
Why it's wrong here
Versioning does not affect access control.
✓
Modify the bucket policy to remove the Allow effect for Principal "*".
Why this is correct
This removes the public access permission.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable default encryption on the bucket.
Why it's wrong here
Encryption does not prevent public access.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think only the bucket policy needs fixing, overlooking that ACLs can independently grant public access, so both the policy and ACL must be remediated.
Detailed technical explanation
How to think about this question
S3 access control is evaluated using both bucket policies and ACLs, with the most permissive grant winning unless an explicit deny exists. The bucket policy in this question grants s3:GetObject to all principals, but if the bucket ACL also has a public read grant (e.g., AllUsers group), removing the ACL grant alone would still leave the policy granting access. Conversely, modifying the policy alone might leave the ACL grant active. Therefore, both the policy and ACL must be addressed to fully remediate public access. AWS recommends using S3 Block Public Access settings as a preventive control.
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.
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Remove the public access grant from the bucket ACL. — Option A is correct because the bucket ACL may still grant public access even if the bucket policy is the primary issue. Removing the public access grant from the ACL ensures that no anonymous principals have s3:GetObject permissions via ACLs, which is a separate access control mechanism from bucket policies. This is a direct remediation step to eliminate public read access.
What should I do if I get this DVA-C02 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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A developer wants to ensure that an S3 bucket is not publicly accessible. Which TWO measures should the developer implement?
easy
A.Enable S3 server access logging.
B.Enable versioning on the bucket.
C.Enable default encryption on the bucket.
✓ D.Review the bucket policy to ensure it does not allow public access.
✓ E.Enable S3 Block Public Access settings on the bucket.
Why D: Blocking public access at the account or bucket level (A) and ensuring no bucket policy grants public access (B) are both necessary. (C) is about encryption at rest, not access. (D) is about versioning. (E) is about logging.
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This DVA-C02 practice question is part of Courseiva's free Amazon Web Services 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 DVA-C02 exam.
Question Discussion
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