Quiz

2948 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 areas2948 Architecture Fundamentals91 Distributed Systems101 Data Architecture90 Cloud Architecture87 Networking96 API & Integration Architecture87 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

3 questions in Transactions & Isolation.

Quiz

A fashion marketplace lets sellers update inventory while customers are checking out. How should reservations, optimistic concurrency, expiry, retries and failed payments interact to prevent overselling?

A financial application runs at read-committed isolation. Two concurrent transactions each read an account balance, check it is sufficient, and debit it. Both succeed and the account goes negative. What happened, and which fixes are correct?

A rule requires at least one engineer on call. Two engineers simultaneously remove themselves; both transactions check the rule, both pass, both commit. Nobody is on call. Name the anomaly and three fixes.