Question bank / Software Engineering, System Design, Advanced
How to answer: Design a globally available order-status tracking service.
Whether you design for failure across regions, and are honest about consistency.
What the interviewer is testing.
Event flow, consistency, regional failure. Whether you design for failure across regions, and are honest about consistency.
An outline for this question.
- Clarify what status means: how fresh must it be, and who reads it, customers or internal tools.
- Publish each order event to a log, and build a read-optimised view of the latest status per order.
- Replicate across regions. Say where you accept slightly stale reads and where you need the latest state.
- Cover a region failing: route traffic away, replay events, and make updates idempotent.
The mistake to avoid.
Promising instant global consistency. Say what you trade for availability, and why it is fine for status.
The general method: requirements, design, trade-offs.
The same shape works for most system design questions, whatever the topic.
- Pin down what the system must do, how many users, and what matters most (speed, cost, correctness).
- Sketch the main parts and how data moves between them, starting simple.
- Pick one or two parts to go deep on, and say what you gave up for each choice.
- Finish with how it fails and how you would know: monitoring, retries, limits.
Practice it, out loud.
Reading an outline is not the same as saying it. Answer this question in a mock interview, in your own words, then compare it with the outline above.
More to practice.
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This is a Replysis practice question. It is not a leaked or official question from any company, and the outline is a guide to structure, not a script. Use your own experience and facts.