Karl demonstrated clear structure, strong breadth across requirements, and thoughtful trade-off discussions. Timing and communication were well-managed, and he connected architectural choices to reliability and scalability concerns.
Areas of Strength
- Functional requirements: Enumerated all requirements, including payment with 3rd party vendors.
- Non-functional requirements: Captured with clear, concrete metrics.
- Time management: ~8 minutes on requirements alignment, ~22 minutes on high-level design, ~15 minutes on deep dive. Could improve further by presenting the HLD more concisely.
- High-level design: Provided detailed design to cover the majority of the use cases.
Areas for Improvement
- Validate design with Functional Requirements: For junior and mid-level engineers, the top priority is ensuring your design fully meets all functional requirements. Focus on covering every requirement and support it with a clear, detailed discussion of the data flow.
- Prepare common design patterns: such as scaling DB, partition and replication, common failure cases like kafka failover.
- Avoiding proposed ideas you are not familiar: Suggest ideas for both functional and non-functional requirements, then validate with interviewers—rather than directly asking them what to cover.
- Engage and align: Actively check for alignment by asking clarifying questions, e.g., “Do you think there are enough details here, or should I go deeper?”
- Highlight trade-offs: For key design decisions, proactively call out the trade-offs and justify why you’d lean toward one option.
Suggestions
Instead of jumping directly into each component, take time to first understand the question holistically. This allows you to identify and prepare the unique and important discussion topics that will add the most value. Once these core points are clear, you can dive into the individual components with stronger structure and focus.
