The answer is that bucket policies can grant access to users in other AWS accounts, while ACLs are a legacy access control mechanism still supported for backward compatibility. This is correct because bucket policies use a JSON-based resource-based policy language that explicitly allows cross-account access by specifying the target account ID or ARN, whereas ACLs are limited to granting basic read/write permissions to predefined groups like AllUsers or AuthenticatedUsers and cannot natively support fine-grained cross-account delegation. On the AWS Certified Data Engineer Associate DEA-C01 exam, this distinction tests your understanding of modern versus legacy S3 security models—a common trap is assuming ACLs are the preferred method for cross-account access, when in fact bucket policies or IAM roles are recommended. Remember the memory tip: "Policies are powerful and precise; ACLs are ancient and basic."
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. 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.
Which TWO statements are true about Amazon S3 bucket policies and ACLs?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ACLs are a legacy access control mechanism that is still supported.
Option B is correct because ACLs (Access Control Lists) are indeed a legacy access control mechanism that Amazon S3 continues to support for backward compatibility. While bucket policies and IAM policies are the modern, recommended approach, ACLs can still be used to grant basic read/write permissions to AWS accounts or predefined groups like AllUsers or AuthenticatedUsers.
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.
✗
When both exist, bucket policies are evaluated before ACLs.
Why it's wrong here
Both are evaluated, but ACLs are evaluated first.
✓
ACLs are a legacy access control mechanism that is still supported.
Why this is correct
ACLs are older but still functional.
Related concept
Read the scenario before looking for a memorised answer.
✗
ACLs can grant permissions to all authenticated AWS users.
Why it's wrong here
ACLs can grant permissions to specific AWS accounts or groups, not all authenticated users.
✗
ACLs support conditions such as IP address restrictions.
Why it's wrong here
ACLs do not support conditions; bucket policies do.
✓
Bucket policies can grant access to users in other AWS accounts.
Why this is correct
Bucket policies can specify cross-account principals.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse ACLs with bucket policies, assuming ACLs support advanced conditions like IP restrictions or that bucket policies and ACLs are evaluated in a strict order, when in fact ACLs are simplistic and both are evaluated as an OR.
Detailed technical explanation
How to think about this question
Under the hood, S3 evaluates access control by combining IAM policies, bucket policies, and ACLs using a union model — if any policy grants access and no explicit deny exists, the request is allowed. ACLs operate at the resource level and use a fixed set of permissions (READ, WRITE, READ_ACP, WRITE_ACP, FULL_CONTROL) with no support for conditions, making them inflexible for scenarios like restricting access by IP or requiring MFA. In real-world migrations, organizations often disable ACLs entirely using the bucket's Object Ownership setting to enforce policy-only access 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.
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: ACLs are a legacy access control mechanism that is still supported. — Option B is correct because ACLs (Access Control Lists) are indeed a legacy access control mechanism that Amazon S3 continues to support for backward compatibility. While bucket policies and IAM policies are the modern, recommended approach, ACLs can still be used to grant basic read/write permissions to AWS accounts or predefined groups like AllUsers or AuthenticatedUsers.
What should I do if I get this DEA-C01 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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This DEA-C01 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 DEA-C01 exam.
Question Discussion
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