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Quiz

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

56 questions in Legacy Modernization.

  1. Application Decomposition advanced

    A legacy system has no clean boundaries to extract — one shared database, entangled modules, no tests. What is the first move, and in what order should capability be recovered?

    3 min answer legacyseamscharacterisation-testsdecomposition
  2. Application Decomposition advanced

    A platform decomposes a monolith into services. Which boundaries should be extracted first, and which extraction produces a distributed monolith?

    2 min answer decompositionboundariescouplingdistributed-monolith
  3. Application Decomposition advanced

    During a monolith decomposition, the new search service needs data owned by five other services. What do you do?

    2 min answer airbnbdecompositiondata-ownershipcqrs
  4. Application Decomposition advanced

    How would you identify where to split a large application, using evidence rather than opinion?

    2 min answer decompositionchange-correlationseamsdata
  5. Coexistence Patterns advanced

    A migration will take eighteen months, during which old and new systems both serve production. How should the coexistence period be designed?

    2 min answer digitcoexistenceroutingconsistency
  6. Coexistence Patterns advanced

    During a multi-year migration, old and new systems must coexist. Which coexistence patterns are sustainable and which accumulate debt?

    2 min answer coexistencedual-writeownershipreconciliation
  7. Coexistence Patterns advanced

    Eighteen months into a coexistence period, customer records are authoritative in the new system and order records are still authoritative in the old one. A refund credits the customer and cancels the order line. What happens the first time the credit commits and the cancellation is rejected?

    3 min answer coexistencewrite ownershipsagascompensation
  8. Coexistence Patterns advanced

    Old and new stores both hold 42 million customer records during a coexistence period. The nightly full-row comparison now takes 6 hours 40 minutes against a 4-hour window, and the legacy side serves the export at about 1800 rows per second. Roughly what does a hash-bucket comparison cost instead, and which assumption decides whether it fits?

    3 min answer coexistence-patternsreconciliationmerklehashing
  9. Coexistence Patterns advanced

    Your cutover plan says switch reads, then switch writes, then decommission. A reviewer asks what happens at 02:00 if the new store turns out to be wrong after writes have moved. What mechanism makes the write switch reversible, and what is the honest unavailability window?

    3 min answer youtubevitesscutoverreverse-replication
  10. Cutover Planning advanced

    Alibaba Cloud reported a peak of 583,000 orders per second during Singles' Day on 11 November 2020. Your own platform is far smaller but its annual peak is roughly 40 times a median day and its date is known a year in advance. How does that one fact reshape an eighteen-month migration plan?

    3 min answer alibabapeak eventscutoverfreeze
  11. Data Migration Strategies advanced

    A platform must migrate very large volumes of file data between storage systems. Which strategies apply, and what dominates the schedule?

    2 min answer data-migrationbulk-transferverificationcutover
  12. Data Migration Strategies advanced

    A shipping platform must migrate years of order and tracking data to a new store. What strategy handles both the historical bulk and the ongoing changes?

    2 min answer shiprocketdata-migrationcdcbackfill