Practice: System Design Interview Preparation

Before answering, separate the feature a user needs from the quality target that constrains it. State any assumptions you make about the video service; the prompt does not specify its audience or traffic.

Identifying system requirements

Write your requirements before opening the suggested answer. Check that each functional requirement describes an action and each nonfunctional requirement can be made measurable.

Scoping the problem

For each question you ask, add one sentence explaining which design decision its answer would affect. A question about video size, for example, should help you reason about the data or load rather than merely extend the requirements list.