easyMultiple Choice
MLA-C01 SSE-KMS Practice Question
An e-commerce company uses a SageMaker endpoint to serve a product recommendation model. The model is retrained every month using batch transforms. The ML team has set up a retraining pipeline using SageMaker Processing jobs and Step Functions. Recently, the Step Functions workflow has been failing at the retraining step with an error: 'AccessDeniedException: User: arn:aws:sts::123456789012:assumed-role/RetrainingRole/abc123 is not authorized to perform: s3:GetObject on resource: arn:aws:s3:::training-data/processed/latest.parquet'. The team confirms that the S3 bucket exists and the object is present. The retraining role has the following policy: { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": [ "s3:GetObject", "s3:PutObject" ], "Resource": "arn:aws:s3:::training-data/*" } ] }. The team also verifies that the bucket policy does not explicitly deny access. What is the MOST likely cause of the AccessDenied error?
⚠ Common exam trap
The trap is focusing only on the S3 permissions in the policy and overlooking the KMS permission requirement for SSE-KMS encrypted objects; candidates must remember that AccessDenied on GetObject can stem from missing kms:Decrypt even when s3:GetObject is allowed.
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 training data object uses server-side encryption with AWS KMS (SSE-KMS), and the retraining role lacks kms:Decrypt permission on the KMS key
The error is an AccessDeniedException on s3:GetObject despite the role having s3:GetObject permission on the bucket. When an S3 object is encrypted with SSE-KMS, the caller must also have kms:Decrypt permission on the KMS key used to encrypt the object. The retraining role's policy only grants S3 permissions, not KMS permissions, so the GetObject call fails. This is the most likely cause given the policy shown.
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 Step Functions execution role does not have permission to invoke the SageMaker Processing job
Why it's wrong here
The error message specifically mentions the retraining role, not the Step Functions execution role. An issue with the execution role would result in a different error (e.g., 'AccessDenied' on invoking the Processing job), not on S3 GetObject.
- ✗
The path in the error message is misspelled; the actual object is at a different key
Why it's wrong here
The policy grants s3:GetObject on arn:aws:s3:::training-data/*, which matches the reported key, and the bucket policy has no explicit deny, so a typo cannot be the cause. This distractor is tempting because key mismatches do produce AccessDenied, but the stem confirms the object exists at that path.
- ✗
The S3 bucket has a bucket policy that denies access to the retraining role based on a condition like aws:SourceIp
Why it's wrong here
A bucket policy denying by `aws:SourceIp` would produce this error, but the stem states the bucket policy contains no explicit deny. That condition-based denial is the right diagnosis when a policy exists yet traffic originates outside the permitted CIDR range — here, the identity policy's resource ARN is the actual mismatch.
- ✓
The training data object uses server-side encryption with AWS KMS (SSE-KMS), and the retraining role lacks kms:Decrypt permission on the KMS key
Why this is correct
The identity policy already grants s3:GetObject on the object, and no bucket policy denies it, so the denial must come from elsewhere. SSE-KMS objects require kms:Decrypt on the key; without it, S3 returns AccessDenied even when the object exists.
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 |
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This MLA-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 MLA-C01 exam.