DEA-C01 Data Operations and Support Practice Question
A data engineer needs to ensure that data in an Amazon S3 bucket is not publicly accessible. Which TWO measures should the engineer implement? (Choose TWO.)
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
✓
Attach a bucket policy that denies access to 'Principal': '*' unless specific conditions are met.
Option A is correct because an S3 bucket policy with an explicit Deny for 'Principal': '*' (optionally scoped by conditions such as aws:SourceIp or aws:SourceVpce) overrides any Allow and prevents anonymous or public access to the bucket's objects. Option C is correct because S3 Block Public Access provides account-level and bucket-level controls (BlockPublicAcls, IgnorePublicAcls, BlockPublicPolicy, RestrictPublicBuckets) that reject public ACLs and public bucket policies, which is the primary AWS safeguard against accidental public exposure. Option B is incorrect because a lifecycle policy only transitions or expires objects and has no effect on access permissions. Option D is incorrect because S3 Versioning only retains multiple object versions for recovery and does not restrict who can read the data. Option E is incorrect because default encryption protects data at rest but does not prevent public read access to the bucket or its objects.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Attach a bucket policy that denies access to 'Principal': '*' unless specific conditions are met.
Why this is correct
A bucket policy denying Principal '*' blocks anonymous and cross-account public access, satisfying the requirement that objects remain non-public. Adding conditions restricts even authenticated principals, closing the common misconfiguration where ACLs or Block Public Access alone leave policy-based exposure.
- ✗
Create a lifecycle policy to delete objects after 30 days.
Why it's wrong here
A lifecycle policy deletes objects on a schedule and never alters bucket or object access permissions, so public exposure persists. It is tempting because lifecycle rules genuinely reduce risk by removing stale data, which is the right control when retention limits, not public access, are the requirement.
- ✓
Enable S3 Block Public Access settings on the bucket.
Why this is correct
S3 Block Public Access overrides bucket policies and ACLs, rejecting any request that would grant public access regardless of existing permissions. This directly satisfies the stem's requirement that bucket data remain non-public, providing account- and bucket-level enforcement that supersedes permissive configurations.
- ✗
Enable S3 Versioning on the bucket.
Why it's wrong here
S3 Versioning retains multiple object versions and does not change any access control, so a public bucket policy still exposes the data. It is tempting because versioning protects against accidental overwrites and deletions, which is the correct control when recoverability, not public accessibility, is the concern.
- ✗
Enable default encryption on the bucket.
Why it's wrong here
Default encryption protects data at rest but does not restrict who may read objects, so anonymous public access remains possible. It is tempting because encryption is a core S3 security control, and it would be correct when the requirement is protecting stored data from unauthorised physical or backend access.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.