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2627 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 areas2627 Architecture Fundamentals81 Distributed Systems101 Data Architecture90 Cloud Architecture77 Networking86 API & Integration Architecture78 Reliability & Resilience88 Observability81 Performance & Capacity Engineering90 Security Architecture85 Cost Architecture & FinOps82 Business Architecture93 Architecture Communication91 Enterprise Architecture91 Legacy Modernization82 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

82 questions in Legacy Modernization.

  1. Data Migration Strategies beginner

    A 6 TB order history must be backfilled into a new store before cutover. The link sustains 1 Gbps and the target ingests about 40 MB/s per writer. Roughly how long is the backfill, and which assumption decides whether it fits one weekend?

    2 min answer backfillcapacity-planningmigrationiops
  2. 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
  3. 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
  4. Data Migration Strategies advanced

    Month 1 of a migration, the reference tables for currency and tax class are copied to the new store and verified row for row. Month 9, a regulator forces a new tax class into the legacy system. Month 11, the new system starts rejecting about 1 order in 400 with a validation error nobody can reproduce in test. What failed, and which design decision made it possible?

    3 min answer reference datadriftcoexistencevalidation
  5. Data Migration Strategies advanced

    The source data contains records that violate the target's constraints. How do you handle it and who decides?

    2 min answer data-migrationqualityprofilingbusiness-decisions
  6. Database Migration advanced

    A billing platform is extracting services from a shared database. Should the code be split first or the data?

    2 min answer chargebeedecompositiondatabaseownership
  7. Database Migration advanced

    A product must move its primary data store while remaining live, with no acceptable data loss. What is the migration sequence, and where do these go wrong?

    2 min answer database-migrationdual-writeverificationcutover
  8. Database Migration beginner Multiple choice

    A team plans to move 2.5 TB to a new database by taking the application offline at 22:00 on Saturday, restoring a backup into the new store, and switching over by 08:00 Sunday. The data copies fine in a test at one tenth the volume. Why does this plan usually fail before it is executed?

    3 min answer cutoverrestorerollbackmaintenance window
  9. Database Migration advanced

    An online schema change is needed on a billion-row MySQL table with zero downtime. Compare trigger-based, binlog-based and native approaches, and describe how the change is gated and reverted.

    3 min answer schema-changegh-ostpt-online-schema-changemysql
  10. Database Migration advanced

    Walk through migrating a live database to a different engine with no downtime. Where does reversibility end?

    2 min answer migrationverificationshadow-readsreversibility
  11. Decommissioning intermediate

    A migration is complete and the old system is still running a year later. Why does decommissioning fail, and what makes it happen?

    2 min answer nykaadecommissioningcostrisk
  12. Decommissioning intermediate

    A replaced system is still running two years after its replacement went live. Why does decommissioning fail, and what makes it happen?

    2 min answer decommissioningunknown-consumersevidenceownership