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DoorDash·Machine Learning Engineer·Technical Phone Screen·Senior

Senior
Jun 2026

Summary

Interviewed for an ML engineer role at DoorDash and got asked about AWS experience in the context of machine learning work. Pretty standard technical screen, nothing too wild.

Questions Asked (1)

Q1

How have you used AWS services in your machine learning projects?

System DesignTechnical Trade-offs
Author's notes

Talked through a few projects where I used SageMaker and S3, maybe leaned too hard on the infrastructure side and not enough on the actual modeling decisions.

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AI HintsAI Generated

Suggested Approach

Structure your answer around a specific ML project, highlighting the AWS services used at each stage of the ML lifecycle. Emphasize the trade-offs and reasons for choosing those services, and connect them to business impact like scalability, cost, or latency.

Pro tip: Focus on why you chose specific AWS services over alternatives, and quantify the impact (e.g., reduced training time by 40%, cut costs by 30%). This shows you understand trade-offs, not just tools.

1. Set the context

Briefly describe the ML project, its goal, and the scale (data size, model complexity, latency requirements). This helps the interviewer understand the constraints that drove your AWS choices.

2. Map AWS services to ML lifecycle stages

Walk through the stages: data ingestion (e.g., Kinesis, S3), preprocessing (e.g., Glue, EMR), training (e.g., SageMaker, EC2), deployment (e.g., SageMaker endpoints, Lambda), and monitoring (e.g., CloudWatch). Explain which services you used and why.

3. Highlight trade-offs and decisions

Discuss key decisions: why you chose a particular service over alternatives (e.g., SageMaker vs. custom EC2), how you optimized cost/performance, and any challenges you faced and resolved.

4. Quantify the impact

Share measurable outcomes: improved model accuracy, reduced training time, lower inference latency, cost savings, or scalability improvements. This demonstrates business value.

5. Reflect and connect to DoorDash

Summarize lessons learned and how you would apply them to DoorDash's ML challenges, such as real-time delivery prediction or personalization at scale.

Key Points to Mention

  • Amazon SageMaker for end-to-end ML workflow (training, tuning, deployment)
  • S3 for data storage and versioning, and its integration with other AWS services
  • AWS Glue or EMR for data preprocessing and feature engineering at scale
  • Real-time inference with SageMaker endpoints or Lambda, and handling latency requirements
  • Cost optimization strategies, such as spot instances for training or auto-scaling for inference
  • Monitoring and logging with CloudWatch, and model retraining pipelines

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.