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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 Separation of Concerns.

  1. Separation of Concerns intermediate

    A ride-hailing company moving off its monolith found engineers actively avoiding service calls because they could not see the latency or the failures those calls produced. Lyft's published answer was Envoy, open-sourced in September 2016: a separate process on every host that all service traffic flows through. Which concern was actually separated, what did the separation cost, and when is a shared library the better answer?

    3 min answer lyftenvoysidecarcross-cutting-concern
  2. Separation of Concerns beginner Multiple choice

    A user signup request takes 4 seconds at p99. Tracing shows the handler sends a welcome email through a third-party API and writes to a CRM before returning. What is wrong architecturally?

    2 min answer separation-of-concernsasyncavailabilitycoupling
  3. Separation of Concerns advanced

    An AI inference platform handles authentication, quota accounting, prompt assembly, safety filtering, model invocation, token counting, billing emission and response streaming in one request handler. Latency is currently fine. Argue for or against separating these concerns, and identify which separations pay for themselves first.

    2 min answer separation-of-concernsinferenceanthropicscenario
  4. Separation of Concerns advanced

    An issue tracker with local-first behaviour keeps a client-side store, a sync engine, and a server. A product manager asks for a new field on an issue. In a well-separated design, how many places should change, and what does the answer tell you?

    1 min answer separation-of-concernslinearlocal-firstsync
  5. Separation of Concerns intermediate

    Review this. Forty live experiments. Each feature calls a central assignment service synchronously when it needs a variant - up to 7 calls on one page render at roughly 9 ms each - and each feature emits its own exposure metric with its own field names. What would you change, what would you leave alone, and what breaks when that service is slow?

    3 min answer booking.comexperimentationcross-cutting concernsdeterminism