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Quiz

2988 questions of the kind that actually get asked — in interviews, in architecture review boards, and by the person who has to run the thing at 3 AM. Every answer states the trade-off rather than the slogan, and says when the obvious choice is the wrong one.

All areas2988 Architecture Fundamentals91 Distributed Systems111 Data Architecture100 Cloud Architecture97 Networking96 API & Integration Architecture97 Reliability & Resilience99 Observability92 Performance & Capacity Engineering100 Security Architecture105 Cost Architecture & FinOps102 Business Architecture103 Architecture Communication102 Enterprise Architecture100 Legacy Modernization102 AI-Era Architecture106 Software Architecture & Engineering93 Architecture Patterns94 Architecture Decision-Making101 The Architect's Meta-Skills102 Delivery & Release Engineering103 Platform Engineering & Developer Experience102 Testing & Quality Architecture102 Data Platform Architecture98 Streaming & Real-Time Data103 Data Governance & Semantics91 Frontend & Experience Architecture101 Edge, Mobile & IoT98 Regulatory & Data Protection Architecture99 Assurance, Audit & Model Risk98
Difficulty Any beginner intermediate advanced

2988 questions.

  1. Testing & Quality Architecture advanced

    How would you decide whether your test suite is worth what it costs?

    2 min answer testingvalueflakinessconfidence
  2. Query Optimisation advanced

    A query that ran in 50ms for two years now takes 90 seconds. Nothing was deployed and the data volume grew normally. What happened?

    2 min answer plannerstatisticsplan-flipdiagnosis
  3. Query Optimisation advanced

    A report query that ran in 90 ms for a year now takes 25 seconds. No code changed, the table grew 4% that week, and a statistics refresh ran overnight. What happened, and what do you do in the next hour as against the next month?

    3 min answer query plannercardinality estimationplan stabilitystatistics
  4. Query Optimisation intermediate Multiple choice

    An endpoint's p99 is 4 seconds. The database's slow query log is empty and CPU is low. What is happening?

    2 min answer n-plus-oneperformancedebugginggithub
  5. Query Optimisation advanced

    In a multi-tenant platform where every tenant's data shares the same physical tables and tenants differ in size by orders of magnitude, why do query plans that are optimal for one tenant become pathological for another - and what is the fix?

    2 min answer query-optimisationmulti-tenancystatisticsplan-caching
  6. Queueing Theory intermediate

    A capacity review shows services running at 85% CPU. Finance suggests raising it to 95% to save money. What is your response?

    2 min answer capacitylatencycost
  7. Queueing Theory beginner

    A checkout service can serve 100 requests per second and receives 60 per second all day. Why do requests still spend time waiting, and what would have to be true for the wait to be zero?

    3 min answer queueingvariabilityburstinessbeginner
  8. Queueing Theory advanced Multiple choice

    A platform runs its worker fleet at 85% average utilisation to control cost. Queue times are becoming unpredictable. What does queueing theory say is happening?

    2 min answer browserstackqueueingutilisationlatency
  9. Queueing Theory advanced

    An inference service's utilisation rises from 70% to 90% and latency more than triples. Why is the relationship non-linear, and what does that imply for capacity planning?

    2 min answer queueing-theoryutilisationlatencyvariability
  10. Queueing Theory advanced

    WeChat's DAGOR overload control, published at SoCC 2018, profiles a server's load from the average waiting time of requests in its pending queue rather than from CPU utilisation, sheds by business and user priority, and propagates admission levels between services. Why is queuing time the right signal, and why does the propagation matter more than the shedding?

    3 min answer tencentwechatdagoroverload control
  11. RAG Architecture advanced

    A RAG system returns fluent answers that are frequently wrong. Where in the pipeline is the problem most likely, and how would you find out?

    2 min answer meeshoragretrievalevaluation
  12. RAG Architecture intermediate

    A business unit wants an assistant answering questions from 200,000 internal documents. They ask whether to fine-tune a model or use retrieval. How do you decide?

    2 min answer airagfine-tuningarchitecture