DEA-C01 Data Ingestion and Transformation Practice Question
Network Topology
A data engineer is troubleshooting a Lambda function that reads from the Kinesis stream 'my-data-stream'. The Lambda function is able to read data but occasionally fails with 'KMS.AccessDeniedException'. What is the most likely cause?
⚠ Common exam trap
Many candidates confuse KMS permissions with Kinesis stream permissions, assuming the error is about stream consumption authorization rather than decryption of encrypted data.
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 Lambda function's execution role does not have kms:Decrypt permission for the KMS key.
The KMS.AccessDeniedException indicates that the Lambda function's execution role lacks the kms:Decrypt permission for the AWS KMS key used to encrypt the Kinesis stream. When a Kinesis stream is encrypted with a customer managed KMS key, the consumer (Lambda) must have explicit decrypt permissions on that key to read the data records.
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 Lambda function's execution role does not have kms:Decrypt permission for the KMS key.
Why this is correct
Kinesis encrypts stream data with a customer managed KMS key, so every GetRecords call requires kms:Decrypt. The intermittent KMS.AccessDeniedException means the function's execution role lacks that permission on the key policy, blocking decryption of returned records even though the read itself succeeds.
- ✗
The retention period is too short; increase it.
Why it's wrong here
Retention controls how long records remain in the stream before expiry; it has no bearing on key permissions, so shortening or lengthening it cannot produce a KMS.AccessDeniedException. It is tempting because expired records cause read failures, but those surface as ExpiredIteratorException, not a KMS authorisation error.
- ✗
The stream has too few shards; increase shard count.
Why it's wrong here
Shard count governs throughput and read capacity, not encryption permissions; too few shards causes ProvisionedThroughputExceededException, never KMS.AccessDeniedException. It tempts because scaling shards genuinely fixes throttling. Here the Lambda execution role's KMS decrypt permission on the stream's customer managed key is the actual gap.
- ✗
The Lambda function is not authorized to consume from Kinesis streams.
Why it's wrong here
Kinesis stream reads are governed by IAM and the stream's resource policy, which would return AccessDeniedException, not KMS.AccessDeniedException. It is tempting because the function does consume the stream, but the KMS prefix indicates the failure lies with decrypting data using the customer managed key.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
Go deeper
Related to this question
About these practice questions
One of 1,321 original DEA-C01 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-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 DEA-C01 exam.