Multi-Region Infrastructure Architect — Interview Questions

Option B is strongest: it explains the mechanism of each pattern (not just the definition), names specific conflict resolution strategies for active-active, articulates the trade-offs symmetrically, provides "suitable when" guidance, and introduces the RPO/RTO framing — which is the language business stakeholders use. The trade-off triangle framing positions the architect as a communicator, not just a technician. Multi-region vocabulary: Active-active — a multi-region topology where all regions serve live read and write traffic. Active-passive — a multi-region topology where the standby region replicates data but serves no live traffic. Multi-master — a database configuration that allows writes to multiple nodes. CRDT (Conflict-Free Replicated Data Type) — a data structure that automatically resolves write conflicts. Last-writer-wins — a conflict resolution strategy where the most recent timestamp determines the accepted value. Options C and D are accurate but lack the "suitable when" framing and the stakeholder communication angle.

Option B is strongest: it uses the interview-question-to-stakeholder technique — turning the technical definition into a question the business can answer in plain language. It explains the direct consequence of each answer (RPO → backup frequency, RTO → infrastructure tier), gives concrete examples at three cost levels, and frames the architect's role as facilitating a cost-risk decision rather than imposing a technical answer. The RPO-zero/RTO-zero example anchors the upper bound of cost. DR vocabulary: RPO (Recovery Point Objective) — the maximum acceptable data loss measured in time. RTO (Recovery Time Objective) — the maximum acceptable downtime after a failure. Warm standby — a standby environment running at reduced capacity, ready to scale up on failover. Cold standby — an environment that is not running until a failover is triggered. Synchronous replication — data is written to all replicas before acknowledging success; guarantees zero data loss. Options C and D are accurate but lack the stakeholder question technique and the cost-tier framing.

Option B is strongest: it defines blast radius as a principle (not just a metaphor), structures the discussion across three dimensions, names specific failure modes and their blast radius classification, introduces three named containment mechanisms with their specific role, and provides the exact sentence pattern for a design review conversation — including the percentage quantification that makes the argument actionable. The "100% blast radius for a shared global dependency" insight is the key architectural point. Resilience vocabulary: Blast radius — the scope of impact of a failure; how many users, services, or regions are affected. Bulkhead — an isolation pattern that limits shared resource contention between components. Circuit breaker — a pattern that stops sending requests to a failing dependency to prevent cascading failures. Cell architecture — a topology that partitions users into independent cells to limit failure scope. Global dependency — a component that all regions or services depend on, whose failure affects the entire system. Options C and D are accurate but lack the three-dimension framing and the design review sentence pattern.

Option B is strongest: it grounds the abstract pattern in a specific realistic decision (sync vs. async replication), uses the exact "we made the trade-off of" sentence structure, translates the accepted risk into business-language impact (N transactions to reconcile), explains why the alternative was rejected (latency SLA constraint), introduces the architectural decision record as the documentation artifact, and — crucially — explains why the sentence pattern matters (it forces naming the accepted cost, not hiding it). Architecture communication vocabulary: Trade-off — the explicit exchange of one property for another; in architecture, always name both sides. Architectural Decision Record (ADR) — a document capturing the context, options, decision, and accepted consequences of an architectural choice. Synchronous replication — writes confirmed only after all replicas acknowledge; zero data loss, higher write latency. Asynchronous replication — writes confirmed after local write; replication happens in background; lower latency, potential data loss window. Reconciliation — the process of detecting and resolving inconsistencies after a failure. Options C and D are accurate but lack the specific numeric example and the explanation of why the sentence pattern matters.

Option B is strongest: it identifies the source of resistance (lack of context on specifics and consequences), structures the explanation across three steps that each address a different reason for resistance, gives concrete examples of what "EU data stays in EU" means at the infrastructure level, uses the fine amount to answer the unspoken question rather than as a threat, and reframes the conversation from compliance obstacle to collaborative design — providing three named architectural approaches. That reframe is the communication pattern that distinguishes a senior architect from someone who just delivers requirements. Data governance vocabulary: Data sovereignty — the legal principle that data is subject to the laws of the jurisdiction in which it is located. Data residency — the physical location where data is stored; often a compliance requirement. GDPR (General Data Protection Regulation) — EU regulation governing personal data processing and storage. PII (Personally Identifiable Information) — data that can be used to identify an individual. Data routing — directing data to specific infrastructure based on origin, type, or classification. Options C and D are accurate but lack the three-step structure and the reframe from obstacle to design problem.