Trade-off discipline
State what wins, what loses, and which new evidence would reverse the choice.
Architecture Judgment Index
75 system design decisions beyond the standard question bank
Built for Staff, Principal, Architect, and senior engineering leadership interviews. Practice ambiguous trade-offs, migrations, blast-radius reasoning, multi-region consistency, cost, security, and the judgment behind an architecture review.
75
original questions
10
decision domains
2
complete samples
35–90m
interview depth
10 Senior · 30 Staff · 25 Principal · 10 Distinguished
What the interview is really testing
Architecture judgment under incomplete information
These are not component-recitation prompts. Each scenario forces a candidate to identify the decision, make assumptions explicit, protect invariants, plan failure and recovery, price the options, and lead a realistic change from the system and organization that already exist.
Failure and recovery
Define blast radius, degraded behavior, reconciliation, rollback, and operational proof.
Evolutionary delivery
Move from the current architecture through observable, reversible stages instead of a flag day.
Staff-level influence
Connect technical decisions to ownership, incentives, cost, policy, and cross-team execution.
Coverage
Ten decision domains
Balanced across distributed systems, data, reliability, platform, security, performance, evolution, economics, and leadership.
Distributed Systems & Scale
Partitioning, coordination, overload, state movement, and blast-radius decisions in mature distributed systems.
Data Architecture & Consistency
Transaction boundaries, online migrations, residency, backfills, reconciliation, and truthful derived data.
Reliability, Resilience & Recovery
Cascades, brownouts, rollbacks, regional evacuation, disaster recovery, and measurable dependency risk.
APIs, Events & Integration
Long-lived contracts, event evolution, partner workflows, delivery semantics, acquisitions, and global fairness.
Cloud Infrastructure & Platforms
Paved roads, control planes, deployments, identity, scheduling, capacity, and governed self-service platforms.
Security, Privacy & Multi-Tenancy
Isolation boundaries, key management, deletion, zero trust, side channels, audit evidence, and privileged access.
Performance, Observability & Capacity
Tail latency, SLO policy, telemetry economics, uncertain demand, workload isolation, and silent failure detection.
Architecture Evolution & Migrations
Monolith evolution, stranglers, protocol changes, ownership boundaries, debt portfolios, and reversible decompositions.
Cost & Operational Efficiency
Reliability-aware savings, unit economics, tiering, build-versus-buy, carbon, egress, and commitment risk.
Architecture Leadership & Decisions
Decision quality, cross-team alignment, compliance trade-offs, program recovery, platform retirement, and impact.
75 questions
2 complete public walkthroughs
#001Public
Scale a mature platform tenfold without betting the company on a rewrite
Turn a vague 10× growth mandate into measured bottlenecks, reversible changes, and a sequenced capacity program that keeps today’s customers safe.
IntermediateDistributed Scale55 min
10x ScaleCapacity PlanningTechnical Debt
#002Locked
Assign write ownership in a multi-region active-active product
Design per-domain and per-entity write ownership instead of hand-waving conflicts away with “active-active,” while meeting latency and outage goals.
AdvancedDistributed Scale60 min
Active ActiveConsistencyData Residency
#003Locked
Contain a hot enterprise tenant on a shared compute fleet
Protect normal tenants when one customer creates pathological fan-out, memory pressure, and queue growth without simply dedicating everything.
AdvancedDistributed Scale50 min
Multi TenancyBlast RadiusAdmission Control
#004Locked
Coordinate safety-critical global configuration through network partitions
Distribute feature, routing, and safety policy globally while distinguishing stale-but-safe operation from changes that require quorum.
AdvancedDistributed Scale50 min
Control PlaneConsistencyReliability
#005Locked
Preserve the ordering that matters in a massively partitioned workflow
Replace an impossible global-order requirement with explicit ordering domains, fencing, deduplication, and repair semantics that still protect business invariants.
AdvancedDistributed Scale60 min
Event DrivenConsistencyIdempotency
#006Locked
Rebalance stateful shards while live traffic keeps mutating them
Move ownership and state under continuous writes using epochs, snapshot-plus-log transfer, validation, and a rollback that cannot create split brain.
AdvancedDistributed Scale65 min
Data MigrationZero DowntimeConsistency
#007Locked
Separate a platform control plane from its high-volume data plane
Design authority, caching, convergence, and degradation so management outages do not interrupt serving and stale intent remains diagnosable.
AdvancedDistributed Scale60 min
Control PlaneReliabilityBlast Radius
#008Locked
Degrade a dependency graph under severe overload without guessing
Turn business priority and dependency criticality into coordinated admission, brownout, and recovery policies across a large service graph.
ExpertDistributed Scale75 min
Load SheddingBlast RadiusReliability
#009Public
Migrate a multi-terabyte database without downtime or wishful dual writes
Plan snapshot, change capture, validation, cutover, rollback, and cleanup for a live database whose write rate and long tail make naïve copying unsafe.
IntermediateData & Consistency55 min
Data MigrationZero DowntimeBackfills
#010Locked
Move a transaction boundary after splitting a business domain
Preserve money and inventory invariants when a formerly local transaction spans independently deployed services and retries become normal.
AdvancedData & Consistency55 min
Distributed TransactionsConsistencyEvent Driven
#011Locked
Rebuild materialized views without serving internally inconsistent fiction
Regenerate large derived views while live changes continue, preserving snapshot boundaries, monotonic publication, and visible freshness.
AdvancedData & Consistency50 min
BackfillsConsistencyEvent Driven
#012Locked
Reconcile years of dual writes after partial failures were normalized
Recover truth when two stores have silently diverged, with explicit authority rules, bounded repair, customer impact controls, and recurrence prevention.
AdvancedData & Consistency55 min
ReconciliationDistributed TransactionsAuditability
#013Locked
Place tenant data under conflicting residency and collaboration rules
Model residency as enforceable policy across primary data, derived indexes, telemetry, support access, and cross-region collaboration.
AdvancedData & Consistency65 min
Data ResidencyMulti TenancyCompliance
#014Locked
Design time-travel audit history that remains trustworthy at scale
Support point-in-time reconstruction and defensible audit evidence without turning an event log into an unbounded, privacy-hostile second database.
AdvancedData & Consistency60 min
AuditabilityEvent DrivenPrivacy
#015Locked
Partition high-cardinality entities when the hottest keys keep changing
Design adaptive placement for a workload whose skew shifts faster than manual shard maps, without sacrificing local invariants or creating unbounded movement.
AdvancedData & Consistency65 min
Capacity Planning10x ScaleConsistency
Build the primitives behind the decisions
Pair the index with InterviewVector's Distributed Systems field manual, system design case studies, and the AI Architect track.