Shopping cart quorum tuning
Design the storage layer for a globally distributed shopping-cart service (Dynamo-style) replicated N=3 per key across regions. The product needs 'always writable' carts (adding an item must never fail even during a network partition) but checkout must read a consistent view of the cart. With per-request tunable R and W, how do you set quorums for the add-item path vs the checkout path, and how do you handle a node that's down during a write?
What a strong answer looks like
Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts (data model, bottlenecks, consistency, failure modes) and name the trade-offs you are making.
Clarify5:00 left
Estimate5:00 planned
Design15:00 planned
Deep dive12:00 planned
Failure8:00 planned
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.