The correct answer uses the combination of `kms:ViaService: s3.*.amazonaws.com` and `aws:SecureTransport: true` in the S3 bucket policy. This works because the `kms:ViaService` condition key restricts the KMS key to be used only through the S3 service, ensuring that objects are encrypted with AWS KMS at rest, while `aws:SecureTransport` enforces TLS for all data in transit, blocking any HTTP requests. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your ability to combine service-specific KMS conditions with transport-layer security in a single policy, a common trap being that candidates confuse `kms:ViaService` with `kms:CallerAccount` or forget to explicitly deny non-TLS traffic. A strong memory tip is “ViaService for KMS, SecureTransport for TLS” — think of the S3 service as the only allowed channel for KMS encryption, and TLS as the mandatory lock on the data pipeline.
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 data engineer needs to ensure that an S3 bucket is encrypted at rest using AWS KMS. The bucket policy must allow only a specific IAM role to access the bucket and enforce encryption in transit. Which combination of bucket policy statements should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use kms:ViaService: s3.*.amazonaws.com and aws:SecureTransport: true
Option C is correct because it uses the kms:EncryptionContext condition to enforce KMS encryption and aws:SecureTransport for TLS. Option A is wrong because it requires SSE-S3, not KMS. Option B is wrong because it allows any KMS key. Option D is wrong because it allows access without encryption in transit.
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 kms:ViaService: s3.*.amazonaws.com and aws:SecureTransport: true
Static NAT maps one inside address to one outside address.
✗
Use s3:x-amz-server-side-encryption: AES256 and aws:SecureTransport: true
Why it's wrong here
AES256 is SSE-S3, not KMS.
✗
Use s3:x-amz-server-side-encryption-aws-kms-key-id and aws:SourceIp
Why it's wrong here
SourceIp is not encryption in transit.
✗
Use kms:EncryptionContext: service:s3 and aws:SecureTransport: true
Why it's wrong here
EncryptionContext alone doesn't enforce KMS key.
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.
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 kms:ViaService: s3.*.amazonaws.com and aws:SecureTransport: true — Option C is correct because it uses the kms:EncryptionContext condition to enforce KMS encryption and aws:SecureTransport for TLS. Option A is wrong because it requires SSE-S3, not KMS. Option B is wrong because it allows any KMS key. Option D is wrong because it allows access without encryption in transit.
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.
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Question Discussion
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