20 questions for the AWS Machine Learning Engineer Associate (MLA-C01) exam, taken from our 59-question bank and spread across its 4domains by their weighting. No sign-up needed: pick an answer to check it, or open “Show answer & explanation” under any question.
This exam was retired on September 28, 2026. These questions are archive material.
This was the last day the English version could be sat. MLA-C02 replaces it: beta registration opened 1 September 2026, beta testing began 29 September, and general availability is January 14, 2027. It runs 85 questions across 170 minutes and adds generative AI, agentic AI orchestration and expanded Bedrock coverage; the domain structure is unchanged. MLA-C01 remains available in Japanese, Korean and Simplified Chinese until MLA-C02 general availability.
Question 1 · Data Preparation for Machine Learning
A team wants to store, share, and reuse curated features across multiple models and teams, with consistent definitions for training and real-time inference. Which AWS service provides this?
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Correct answer: B
B. Amazon SageMaker Feature Store
SageMaker Feature Store is a repository to store, share, and serve curated features consistently for training (offline) and inference (online). S3 Glacier (A) is cold archival storage, Lambda (C) runs code, and SNS (D) is messaging — none is a feature repository.
Question 2 · Data Preparation for Machine Learning
A team must label thousands of images for a supervised computer vision model, using human labelers with a managed workflow. Which AWS service supports this?
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Correct answer: B
B. Amazon SageMaker Ground Truth
SageMaker Ground Truth provides managed data-labeling workflows (with human labelers and optional automated labeling). Model Monitor (C) watches production models, Glue DataBrew (D) is visual data prep, and Athena (A) queries S3 with SQL — none is a labeling service.
Question 3 · Data Preparation for Machine Learning
Why is it important to split data into separate TRAINING, VALIDATION, and TEST sets?
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Correct answer: B
B. Train the model, tune/select using validation, and get an unbiased final performance estimate on the untouched test set
The training set fits the model, the validation set guides tuning/model selection, and the held-out test set gives an unbiased estimate of real-world performance. Option D is false (splitting doesn't add data), and options A and C invent nonexistent reasons.
Question 4 · Data Preparation for Machine Learning
For an ML training job reading millions of records from S3, which combination improves read efficiency and cost?
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Correct answer: A
A. Store data as compressed, columnar Parquet and partition it in S3 by a relevant key
Compressed columnar Parquet plus sensible S3 partitioning reduces bytes scanned and speeds reads, lowering cost and training time. A single giant uncompressed CSV (B) and millions of tiny objects (C) are both inefficient, and SNS (D) is a messaging service, not storage.
Question 5 · Data Preparation for Machine Learning
An outlier detection review finds a few sensor readings of -9999 (a device error code) mixed into a temperature feature. What is the BEST data-preparation action?
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Correct answer: A
A. Treat -9999 as invalid/missing and handle it (remove or impute), since it's an error code, not a real temperature
Sentinel error codes like -9999 aren't real measurements; treat them as invalid/missing and remove or impute them so they don't skew the model. Keeping them (D) injects extreme false values, and options B and C corrupt the feature.
Question 6 · Data Preparation for Machine Learning
To detect whether a training dataset is biased against a demographic group before model training, which SageMaker capability should you use?
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Correct answer: C
C. Amazon SageMaker Clarify
SageMaker Clarify detects bias in datasets (and models) and provides explainability. Neo (B) optimizes models for target hardware, Edge (A) manages edge deployments, and Debugger (D) inspects training runs for issues — not the bias-detection tool for datasets.
Question 7 · ML Model Development
A regression model predicts house prices. Which metric expresses error in the SAME units as the target and penalizes large errors more heavily?
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Correct answer: B
B. Root Mean Squared Error (RMSE)
RMSE is in the target's units and squares errors, penalizing large deviations more — a standard regression metric. Precision, recall, and F1 (B, C, D) are classification metrics and don't apply to predicting a continuous price.
Question 8 · ML Model Development
For a structured tabular classification/regression problem on SageMaker where you want strong performance with minimal deep-learning setup, which built-in algorithm is a common strong choice?
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Correct answer: A
A. XGBoost
XGBoost (a gradient-boosted tree algorithm, available as a SageMaker built-in) is a go-to for tabular classification/regression with strong results and modest tuning. A CNN (B) targets images, speech-to-text (C) targets audio, and a DNS resolver (D) is not an ML algorithm.
Question 9 · ML Model Development
Which SageMaker capability automatically searches hyperparameter combinations to find the best-performing model configuration?
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Correct answer: D
D. SageMaker Automatic Model Tuning (hyperparameter tuning)
SageMaker Automatic Model Tuning runs training jobs across hyperparameter ranges (using strategies like Bayesian search) to find the best configuration. Model Monitor (C) watches production, Ground Truth (A) labels data, and Feature Store (B) manages features — none tunes hyperparameters.
Question 10 · ML Model Development
Why might ACCURACY be a misleading metric for a model trained on a 99:1 imbalanced dataset?
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Correct answer: A
A. A model predicting only the majority class achieves 99% accuracy while catching none of the minority class
With severe imbalance, always predicting the majority class yields high accuracy while completely failing on the important minority class — so precision, recall, and F1 are more informative. Option B is false, option C is false (accuracy is computable), and option D is false (accuracy is a classification metric).
Question 11 · ML Model Development
During hyperparameter tuning, a team wants an efficient search strategy that uses results from prior trials to choose the next hyperparameters intelligently. Which strategy does SageMaker Automatic Model Tuning offer for this?
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Correct answer: B
B. Bayesian optimization
Bayesian optimization models the relationship between hyperparameters and results, using prior trials to pick promising next values more efficiently than random or grid search. Manual guessing (D), leaving values fixed (A), and deleting layers (C) are not tuning strategies.
Question 12 · Deployment and Orchestration of ML Workflows
A real-time endpoint serves a latency-critical feature but the team also needs to periodically score a huge backlog cheaply. What is the BEST combined approach?
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Correct answer: B
B. Use a real-time endpoint for live requests and batch transform for the periodic bulk backlog
Match the inference option to each need: a real-time endpoint for low-latency live requests, and batch transform for cost-efficient offline bulk scoring. Forcing one endpoint for both (D) is costly/awkward, batch transform can't meet live latency (C), and per-record training (A) isn't inference.
Question 13 · Deployment and Orchestration of ML Workflows
Why containerize an ML model with a bring-your-own-container approach on SageMaker?
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Correct answer: C
C. To package custom dependencies and runtime so training/inference is reproducible and portable across environments
Containerization packages code, libraries, and runtime for reproducible, portable execution when built-in images don't fit your needs. It doesn't shrink model files (D), and it neither bypasses IAM (B) nor monitoring (A) — those remain in force.
Question 14 · Deployment and Orchestration of ML Workflows
To bring a custom training or inference environment with specific libraries, a team packages their code and dependencies into a container image. Where do they store this image for SageMaker to use?
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Correct answer: C
C. Amazon Elastic Container Registry (Amazon ECR)
Amazon ECR is the managed container registry where you push custom Docker images that SageMaker pulls for training or inference (bring-your-own-container). Glacier (B) is archival storage, Route 53 (A) is DNS, and Secrets Manager (D) stores secrets — none is a container registry.
Question 15 · Deployment and Orchestration of ML Workflows
To reduce risk when releasing a new model version, a team routes a small percentage of live traffic to the new version and monitors it before full rollout. Which deployment strategy is this?
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Correct answer: A
A. Canary deployment
A canary deployment sends a small slice of traffic to the new version first, monitoring before increasing rollout — limiting blast radius. A big-bang replacement (B) is riskier, batch transform (C) is offline scoring, and 'blue with no green' (D) isn't a valid strategy.
Question 16 · ML Solution Monitoring, Maintenance, and Security
An endpoint shows rising latency and error rates under load. Using CloudWatch, what is an appropriate FIRST response to maintain service quality?
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Correct answer: B
B. Set CloudWatch alarms and enable/adjust auto scaling to add capacity, then investigate the root cause
Alarms plus auto scaling add capacity to protect service quality while you investigate the underlying cause. Ignoring the problem (C) harms users, deleting the model (A) is destructive and premature, and turning off monitoring (D) hides the issue rather than fixing it.
Question 17 · ML Solution Monitoring, Maintenance, and Security
Which combination BEST represents securing an end-to-end ML system on AWS?
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Correct answer: C
C. Least-privilege IAM roles, KMS encryption at rest and TLS in transit, VPC isolation, and CloudTrail/CloudWatch monitoring
End-to-end ML security is layered: least-privilege IAM, encryption at rest (KMS) and in transit (TLS), network isolation (VPC), and monitoring/audit (CloudWatch, CloudTrail). Option B lists anti-practices, option D is insufficient, and option A wrongly assumes the model secures the surrounding system.
Question 18 · ML Solution Monitoring, Maintenance, and Security
Which SageMaker capability provides ongoing bias monitoring and feature-attribution (explainability) drift detection for models in production?
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Correct answer: C
C. Amazon SageMaker Clarify (integrated with Model Monitor)
SageMaker Clarify supports bias detection and explainability, and integrates with Model Monitor to watch for bias drift and feature-attribution drift in production. Neo (A) optimizes models for hardware, Trusted Advisor (B) gives account best-practice checks, and QuickSight (D) is BI — none does production bias/explainability monitoring.
Question 19 · ML Solution Monitoring, Maintenance, and Security
Which service should a team use to continuously monitor a production SageMaker endpoint for data-quality and model-quality drift, with scheduled checks against a baseline?
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Correct answer: B
B. Amazon SageMaker Model Monitor
SageMaker Model Monitor runs scheduled checks against a baseline to detect data-quality and model-quality drift (plus bias and feature attribution drift) on endpoints. Ground Truth (A) labels data, Glue DataBrew (D) preps data, and Comprehend (C) is NLP — none monitors production model quality.
Question 20 · ML Solution Monitoring, Maintenance, and Security
To protect training data and model artifacts, which controls should an ML engineer apply?
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Correct answer: A
A. Encrypt data at rest (e.g., with AWS KMS) and in transit, and restrict access with IAM
Data and artifacts should be encrypted at rest (KMS) and in transit, with IAM restricting access. Public buckets (B), disabled encryption (C), and anonymous access (D) all expose sensitive data and violate security best practices.
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