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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

5 questions in Clocks & Ordering.

  1. Clocks & Ordering advanced

    "Interview. In a multiplayer design tool, two users move the same object at the same moment. Wall-clock timestamps disagree because their machines' clocks differ by 400 ms. How do you decide what the document should show, and what would you say to an engineer who proposes using timestamps?" What is a strong answer?

    2 min answer clocksorderingcausalitylamport
  2. Clocks & Ordering intermediate

    A service's own latency histogram shows a 40-second p99 spike at 03:14 every few weeks, and its logs occasionally record negative request durations. Traces for the same window show every downstream call completing in under 50 ms. Where is the time going?

    3 min answer clocksntpmonotonicinstrumentation
  3. Clocks & Ordering advanced

    An event-processing platform orders records by the timestamp the producing service attached. Records occasionally appear out of order and some appear to arrive before they were created. What is happening and how should ordering be established?

    2 min answer credclocksorderingcausality
  4. Clocks & Ordering advanced

    Spanner uses TrueTime — an API that returns a bounded time interval rather than a timestamp — to provide externally consistent distributed transactions. What problem does this solve, what does it cost, and when is the cost not worth paying?

    2 min answer googlespannertruetimeconsistency
  5. Clocks & Ordering advanced

    Two regions both accept writes to the same user record and resolve conflicts by last-write-wins on timestamp. Users report edits silently disappearing. Explain and fix.

    3 min answer clocksorderingconflict-resolutiondropbox