MLS-C01 Data Engineering Practice Question
A company uses AWS Lake Formation to manage permissions on a data lake stored in Amazon S3. A data analyst tries to query a table using Amazon Athena but receives an 'Access Denied' error. The analyst has SELECT permission on the table in Lake Formation. What is the most likely cause?
⚠ Common exam trap
A common mix-up: candidates assume 'Access Denied' errors are always due to missing IAM permissions or encryption issues, but in Lake Formation, the most common root cause is the S3 bucket not being registered, which prevents Lake Formation from enforcing its permissions.
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
✓
The S3 bucket is not registered with Lake Formation
When Lake Formation manages permissions on a data lake, it requires that the underlying S3 bucket be registered with Lake Formation. If the bucket is not registered, Lake Formation cannot enforce its fine-grained access controls, and Athena will fail with an 'Access Denied' error even if the analyst has SELECT permission on the table in Lake Formation. Registering the bucket allows Lake Formation to integrate with S3 and apply its permission model.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The S3 bucket is not registered with Lake Formation
Why this is correct
If the bucket is not registered, Lake Formation cannot control access, and the default S3 permissions apply, which may deny access.
- ✗
The S3 bucket is encrypted with a KMS key that the analyst does not have access to
Why it's wrong here
KMS permissions might cause an error, but it would be a different error message.
- ✗
The table does not have any partitions defined
Why it's wrong here
Lack of partitions would cause a query to scan all data, but not an Access Denied error.
- ✗
The IAM role used by Athena does not have lakeformation:GetDataAccess permission
Why it's wrong here
This is a possible cause, but typically Lake Formation automatically grants this via the registered bucket.
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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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MLS-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 MLS-C01 exam.