1. Performance vs Cost advanced

    A streaming platform can halve latency by doubling infrastructure cost. How should this trade-off be evaluated?

    2 min answer performancecostbusiness-impactsegmentation
  2. Performance vs Cost advanced

    Alibaba reported a peak of 583000 orders per second during Singles' Day 2020, far above its ordinary daily rate. A retailer with a 40x annual peak asks whether it should provision for peak all year, since that is what the big platforms clearly do. What did a platform in that position actually buy, and where does copying it go wrong?

    2 min answer alibabapeak-capacitydegradationrehearsal
  3. Single vs Multi-Region advanced

    A collaborative product must decide between single-region, multi-region read replicas, and multi-region writable. What should decide it?

    2 min answer multi-regionlatencycomplexitylocal-first
  4. Single vs Multi-Region advanced

    A stakeholder asks for multi-region. What three questions do you ask before agreeing?

    2 min answer multi-regionresidencylatencyavailability
  5. Single vs Multi-Region advanced

    A team must decide whether to run in one region or several. What evidence justifies multi-region, and what does it cost?

    2 min answer flyiomulti-regionlatencyavailability
  6. Reliability vs Complexity advanced

    A proposed architecture is more reliable in theory and substantially more complex to operate. How should that be evaluated?

    2 min answer reliabilitycomplexityoperated-reliabilityfailure-modes
  7. Reliability vs Complexity advanced

    A team can improve availability by adding several components, each of which is itself a failure point. How should that be evaluated?

    2 min answer railwayreliabilitycomplexityfailure-modes
  8. Reliability vs Complexity advanced

    Give an example of a reliability mechanism that made a system less reliable, and explain the mechanism.

    2 min answer reliabilitycomplexityamplificationautomation
  9. Reversibility advanced

    How should reversibility change the process applied to a decision, and which decisions are commonly misclassified?

    2 min answer reversibilityone-way-doorprocessspeed
  10. Security vs Usability advanced

    A consumer finance product must balance fraud controls against onboarding friction. How should that trade-off be made rather than argued?

    2 min answer slicefraudfrictionrisk
  11. Security vs Usability advanced

    A security control materially reduces risk and adds friction to a developer workflow used thousands of times a day. How should the trade-off be made?

    2 min answer securityusabilityfrictionworkarounds
  12. Serverless vs Containers advanced

    A grocery-delivery marketplace moves its order-status API from long-running containers to per-request functions to stop paying for idle capacity overnight; traffic swings about 20x between trough and the evening peak. What did the team buy, and when does the bill arrive?

    2 min answer serverlesscontainersconnection-poolingcold-start