The correct combination is to create a bucket policy that denies `s3:PutObject` unless the `x-amz-server-side-encryption` header is set to `AES256`, and to use S3 Batch Operations to copy existing objects in place with default encryption applied. This works because the bucket policy acts as a gatekeeper, rejecting any upload that lacks the required encryption header, thereby enforcing encryption at rest for all new objects. Meanwhile, S3 Batch Operations can retroactively encrypt objects that were uploaded before the default encryption setting was enabled, addressing the auditor’s finding. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of combining preventive controls (bucket policy conditions) with corrective actions (Batch Operations) to achieve full compliance. A common trap is choosing only default encryption, which does not block unencrypted uploads from clients that omit the header. Memory tip: “Deny the header, batch the past” — the policy denies missing headers, and Batch Operations fix existing objects.
DEA-C01 Data Security and Governance Practice Question
This DEA-C01 practice question tests your understanding of data security and governance. 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 healthcare company stores sensitive patient data in an S3 bucket (bucket name: patient-data-prod). The security team requires that all data be encrypted in transit and at rest, and that access be logged for auditing. The company currently uses S3 default encryption with SSE-S3. An external auditor finds that some objects have been uploaded without encryption because the default encryption setting was not applied to objects uploaded before the setting was enabled. The company wants to prevent any future unencrypted uploads and ensure all existing objects are encrypted. Which combination of actions should the data engineer take? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use S3 Batch Operations to copy all existing objects in place with the 'aws:Replicate' operation to apply default encryption.
To prevent unencrypted uploads, the bucket policy must deny PutObject requests that do not include the x-amz-server-side-encryption header with AES256. To encrypt existing objects, S3 Batch Operations can copy them in place with the default encryption setting applied. Option D alone only covers new objects, not existing ones. Option E is unnecessary because SSE-S3 uses AES256.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Use S3 Batch Operations to copy all existing objects in place with the 'aws:Replicate' operation to apply default encryption.
Why this is correct
Batch Operations can apply encryption to existing objects by copying them in place.
Related concept
Static NAT maps one inside address to one outside address.
✗
Enable S3 Object Ownership and set the bucket ACL to private.
Why it's wrong here
Object Ownership does not enforce encryption.
✗
Enable S3 default encryption on the bucket.
Why it's wrong here
This only affects new objects, not existing ones.
✗
Create a bucket policy that denies s3:PutObject if the x-amz-server-side-encryption-aws-kms-key-id is not present.
Why it's wrong here
The scenario uses SSE-S3, not SSE-KMS.
✓
Create a bucket policy that denies s3:PutObject if the x-amz-server-side-encryption header is not set to 'AES256'.
Why this is correct
This enforces encryption on all new uploads.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Trap categories for this question
Scenario analysis trap
The scenario uses SSE-S3, not SSE-KMS.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
Data Security and Governance — This question tests Data Security and Governance — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Use S3 Batch Operations to copy all existing objects in place with the 'aws:Replicate' operation to apply default encryption. — To prevent unencrypted uploads, the bucket policy must deny PutObject requests that do not include the x-amz-server-side-encryption header with AES256. To encrypt existing objects, S3 Batch Operations can copy them in place with the default encryption setting applied. Option D alone only covers new objects, not existing ones. Option E is unnecessary because SSE-S3 uses AES256.
What should I do if I get this DEA-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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 company has an S3 bucket with versioning enabled and a bucket policy that denies access if the request does not include encryption. A data engineer notices that some objects are not encrypted. What is the most likely cause?
hard
A.The bucket policy does not evaluate requests from the same account.
✓ B.The policy only applies to new uploads; existing objects remain unencrypted.
C.Default encryption was not enabled at the bucket level.
D.Versioning was enabled after the objects were uploaded.
Why B: Option D is correct because bucket policies with deny for unencrypted requests only apply to new uploads, not existing objects. Option A is wrong because bucket policy evaluates all requests. Option B is wrong because versioning does not affect encryption. Option C is wrong because default encryption only applies to new objects.
Variation 2. A company wants to enforce that all data written to an S3 bucket is encrypted with a customer-managed AWS KMS key. The data engineer has created the KMS key and attached an S3 bucket policy. However, users are still able to upload objects without specifying the KMS key. What is the most likely cause?
easy
✓ A.The S3 bucket policy does not include a condition that denies s3:PutObject without the correct encryption
B.The S3 bucket has default encryption enabled with SSE-S3
C.The KMS key policy does not grant the users kms:Encrypt permission
D.The IAM role for the users does not have s3:PutObject permission
Why A: Option C is correct because the bucket policy must explicitly deny PutObject if the encryption header does not match the required KMS key. Option A is wrong because KMS key policy is needed but the issue is the bucket policy. Option B is wrong because the IAM role must allow kms:GenerateDataKey, but the issue is the bucket policy. Option D is wrong because S3 default encryption does not force the use of a specific KMS key.
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Question Discussion
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