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2667 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 areas2667 Architecture Fundamentals81 Distributed Systems101 Data Architecture90 Cloud Architecture87 Networking86 API & Integration Architecture78 Reliability & Resilience88 Observability81 Performance & Capacity Engineering90 Security Architecture95 Cost Architecture & FinOps92 Business Architecture93 Architecture Communication91 Enterprise Architecture91 Legacy Modernization92 AI-Era Architecture86 Software Architecture & Engineering84 Architecture Patterns84 Architecture Decision-Making91 The Architect's Meta-Skills92 Delivery & Release Engineering93 Platform Engineering & Developer Experience92 Testing & Quality Architecture90 Data Platform Architecture88 Streaming & Real-Time Data93 Data Governance & Semantics81 Frontend & Experience Architecture91 Edge, Mobile & IoT88 Regulatory & Data Protection Architecture90 Assurance, Audit & Model Risk88
Difficulty Any beginner intermediate advanced

33 questions in Performance & Capacity.

  1. Bottleneck Analysis intermediate

    A service is slow and the team disagrees about the cause. What method identifies the actual bottleneck rather than the suspected one?

    2 min answer swiggybottleneckmethodmeasurement
  2. Caching for Performance intermediate

    A read-heavy content platform must scale. In what order should caching, replicas, denormalisation, CDN and query optimisation be applied, and what determines the order?

    2 min answer pratilipiread-heavycachingcdn
  3. Caching for Performance intermediate

    A service adds an in-process cache in front of its shared Redis tier to remove a 1 ms round trip. What has the team given up, and at what scale does that bill arrive?

    3 min answer caching-performancenear-cachestalenessinvalidation
  4. Capacity Modelling intermediate Multiple choice

    Alibaba reported a peak of 583,000 order creations per second during Singles' Day in 2020. Suppose one promoted item accounts for 0.5% of those orders and its stock is held in a single row. Roughly how many updates per second does that row have to absorb?

    2 min answer alibabaflash salehot keywrite contention
  5. Capacity Modelling intermediate Multiple choice

    You run in three availability zones and must survive losing one. What is your maximum normal utilisation and why?

    2 min answer capacityheadroomfailure-domainsutilisation
  6. Capacity Modelling intermediate Multiple choice

    Zoom's CEO wrote on 1 April 2020 that maximum daily meeting participants went from roughly 10 million at the end of December 2019 to more than 200 million in March 2020. For any platform absorbing a 20× demand rise over three months rather than three minutes, which capacity decision does the slower surge force that the fast one does not?

    3 min answer zoomcapacity-modellinglead-timequota
  7. Connection Pooling intermediate

    A service scales its application instances from 20 to 200 and the database begins refusing connections. What happened, and what is the correct architecture?

    2 min answer connection-poolingproxyscalingdatabase-limits
  8. Connection Pooling intermediate

    A service works fine at 10 instances. At 60 instances during a peak, the database starts refusing connections. Explain the arithmetic.

    2 min answer poolsscalingdatabases
  9. Horizontal vs Vertical Scaling intermediate

    A service is at capacity. When is vertical scaling the better answer than horizontal, and what is the trap in each direction?

    2 min answer unacademyscalingverticalhorizontal
  10. Horizontal vs Vertical Scaling intermediate Multiple choice

    A workspace product's primary database is at its limits. Should it scale vertically, add replicas, or shard? What order and what evidence?

    2 min answer scalingverticalshardingreplicas
  11. Horizontal vs Vertical Scaling intermediate

    When is vertical scaling the better answer, and what makes horizontal inevitable eventually?

    2 min answer scalingverticalhorizontalavailability
  12. Little's Law intermediate

    A platform must size worker pools for a peak of 50,000 requests per second with a 200ms average service time. How does Little's Law inform the answer, and what does it not tell you?

    2 min answer dream11littles-lawconcurrencycapacity