The answer is to enforce HTTPS for all S3 API requests using a bucket policy and to enable server-side encryption (SSE-S3 or SSE-KMS) on the S3 bucket. HTTPS ensures data in transit is encrypted via TLS, while server-side encryption automatically encrypts objects at rest as they are written to disk, covering both security requirements. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this tests your understanding of the shared responsibility model for data lakes, where the platform handles encryption at rest but you must explicitly enforce encryption in transit via policy. A common trap is confusing client-side encryption with server-side encryption or assuming VPC endpoints or CloudFront alone encrypt data in transit—they do not. Remember the mnemonic: "HTTPS for the highway, SSE for the house."
MLS-C01 Data Engineering Practice Question
This MLS-C01 practice question tests your understanding of data engineering. 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 company is designing a data pipeline to ingest data from multiple sources into an Amazon S3 data lake. The data must be encrypted at rest and in transit. Which TWO actions should be taken to meet these requirements?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable Server-Side Encryption on the S3 bucket
Server-Side Encryption (SSE-S3 or KMS) encrypts data at rest in S3. Using HTTPS (SSL/TLS) for all API calls encrypts data in transit. Client-side encryption is an alternative but not the standard AWS approach. VPC endpoints and CloudFront do not encrypt in transit by themselves.
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.
Static NAT maps one inside address to one outside address.
✗
Enable S3 Transfer Acceleration
Why it's wrong here
Acceleration improves speed, not encryption.
✓
Enforce HTTPS for all S3 API requests using bucket policy
Why this is correct
Ensures data is encrypted in transit.
Related concept
Static NAT maps one inside address to one outside address.
✗
Use client-side encryption before uploading
Why it's wrong here
Not required; server-side encryption is sufficient.
✗
Use S3 VPC Endpoint
Why it's wrong here
VPC endpoints provide private connectivity but do not encrypt.
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 MLS-C01 NAT questions on configuration and troubleshooting.
Data Engineering — This question tests Data Engineering — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Enable Server-Side Encryption on the S3 bucket — Server-Side Encryption (SSE-S3 or KMS) encrypts data at rest in S3. Using HTTPS (SSL/TLS) for all API calls encrypts data in transit. Client-side encryption is an alternative but not the standard AWS approach. VPC endpoints and CloudFront do not encrypt in transit by themselves.
What should I do if I get this MLS-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 MLS-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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