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Netflix·Software Engineer·Onsite - System Design / Architecture·Senior

SeniorPrefer not to say
Jul 2026

Summary

Netflix system design round focused entirely on a data modeling problem for their ad platform. Pretty niche topic if you haven't worked in adtech before, and the scope was way broader than I expected for a single session.

Questions Asked (1)

Q1

Design a data model for tracking a direct-sold demand order in a demand-side advertising platform, covering advertisers, agencies, line items, targeting, creatives, delivery tracking, frequency caps, and auditability.

Data ModelingSystem DesignTechnical Trade-offs
Author's notes

This thing had like ten sub-domains crammed into one question.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the scope and key requirements of the demand-side platform, then propose a normalized relational schema that captures the core entities and their relationships. Emphasize how the model supports scalability, auditability, and efficient querying for delivery and frequency capping.

Pro tip: Highlight the importance of separating transactional and analytical workloads, and discuss how you would handle high-volume delivery tracking with partitioning or time-series databases. Also, mention that auditability often requires immutable logs and versioning of targeting and creative assignments.

1. Clarify Requirements and Scope

Ask questions to understand the scale, key use cases, and constraints (e.g., real-time bidding, reporting needs, compliance). Confirm whether the model should support multiple advertisers and agencies, and how granular delivery tracking must be.

2. Identify Core Entities and Relationships

List the main entities: Advertiser, Agency, Line Item, Targeting Criteria, Creative, Delivery Record, Frequency Cap, and Audit Log. Define their relationships, such as an advertiser having multiple line items, and a line item having multiple creatives and targeting rules.

3. Design the Schema with Scalability in Mind

Propose tables with primary and foreign keys, and consider normalization vs. denormalization for performance. For delivery tracking, suggest partitioning by date and using a columnar or time-series store for analytics.

4. Address Frequency Capping and Auditability

Explain how frequency caps can be enforced using a separate service or a distributed cache, and how audit logs should capture all changes with timestamps and user IDs for compliance.

5. Discuss Trade-offs and Extensions

Talk about trade-offs between consistency and availability, and how the model can evolve to support new targeting types or real-time updates. Mention indexing strategies for common queries.

Key Points to Mention

  • Entity-relationship diagram with Advertiser, Agency, Line Item, Creative, Targeting, Delivery, Frequency Cap, and Audit Log tables.
  • Use of foreign keys and indexes to ensure referential integrity and query performance.
  • Partitioning delivery data by date and using a time-series database for high-volume tracking.
  • Frequency capping implementation via a fast key-value store (e.g., Redis) with TTL and atomic increments.
  • Audit logging with immutable append-only tables and versioning for targeting and creative changes.
  • Consideration of GDPR/CCPA compliance and data retention policies.

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