The answer is to attach the AWS managed policy AmazonS3ReadOnlyAccess to the IAM user. This is the best practice for restricting an overly permissive S3 bucket policy because it replaces broad, open access with a scoped, read-only permission set that still satisfies the required data access needs. By applying this IAM managed policy, you enforce the principle of least privilege at the user level, ensuring the user can only read objects without the ability to write, delete, or modify bucket configurations. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how to combine IAM policies with S3 bucket policies to correct misconfigurations without breaking existing workflows. A common trap is choosing a blanket Deny statement, which would block all operations and disrupt applications, or selecting full access, which defeats the purpose of restriction. Memory tip: think “ReadOnly for the user, not the bucket” — always restrict at the IAM level first before touching the bucket policy.
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. 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 data engineer notices that an Amazon S3 bucket policy is overly permissive. What is the best practice to restrict access while maintaining required permissions?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Attach the AWS managed policy AmazonS3ReadOnlyAccess to the IAM user.
Option A is correct because the AWS managed policy 'AmazonS3ReadOnlyAccess' grants read-only access and is more restrictive than full access. Option B (Deny all) would break applications. Option C (blocklist) is not a standard method. Option D (full access) is the opposite of restriction.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Grant full S3 access using a new IAM policy.
Why it's wrong here
Granting full access would be even more permissive, not restrictive.
✗
Write a new bucket policy that denies all actions.
Why it's wrong here
Denying all actions would block all access, breaking applications that require permissions.
✗
Use an S3 blocklist to restrict access.
Why it's wrong here
S3 does not have a blocklist feature; access control is via policies.
✓
Attach the AWS managed policy AmazonS3ReadOnlyAccess to the IAM user.
Why this is correct
This policy grants only read access to S3, which is more restrictive than the current overly permissive policy.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
Data Operations and Support — This question tests Data Operations and Support — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Attach the AWS managed policy AmazonS3ReadOnlyAccess to the IAM user. — Option A is correct because the AWS managed policy 'AmazonS3ReadOnlyAccess' grants read-only access and is more restrictive than full access. Option B (Deny all) would break applications. Option C (blocklist) is not a standard method. Option D (full access) is the opposite of restriction.
What should I do if I get this DEA-C01 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Standard ACLs match source addresses.
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