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IT
Test your knowledge of SRE principles, Error Budgets, SLIs/SLOs, alerting heuristics, and blameless postmortems. Répondez à chaque question pour savoir si vous avez juste, avec une explication à chaque fois.
Un test d’entraînement gratuit de 16 questions à choix multiples sur IT. Chaque question a une bonne réponse et une courte explication, et le corrigé complet sous le quiz sert aussi de fiche de révision. Sans compte, sans limite de temps — passez-le autant de fois que vous voulez.
Ce quiz gratuit est un QCM de 16 questions. Après chaque réponse, vous voyez si elle est juste, avec une explication à chaque fois. Sans inscription ni limite de temps — refaites-le autant de fois que vous voulez et servez-vous du corrigé ci-dessus pour réviser avant ou après.
Bonne réponse : BSLI is the metric measured; SLO is the internal target for that metric; SLA is the business contract with consequences for missing the target
An SLI (Service Level Indicator) is the metric measured; an SLO (Service Level Objective) is the target reliability goal; an SLA (Service Level Agreement) is the business contract with penalties.
Bonne réponse : BThe acceptable threshold of unreliability (100% minus SLO) that can be spent on shipping features, changes, and deployments
An Error Budget is calculated as (1 - SLO); it represents the allowable level of service imperfection that teams can 'spend' on deployments, experiments, and innovation.
Bonne réponse : BFeature launches are halted, and engineering effort pivots strictly to reliability, testing, and technical debt
When an error budget is depleted, the agreed-upon policy mandates halting risky feature launches to refocus engineering bandwidth on stabilizing the platform.
Bonne réponse : BIt alerts based on the rate at which the error budget is being consumed over multiple time windows, avoiding false positives from transient blips
Burn rate alerts track the speed of error budget consumption across short and long time windows simultaneously, catching critical outages fast while eliminating noisy transient alerts.
Bonne réponse : BRepetitive, manual, automatable work that scales linearly with service growth and lacks enduring engineering value
Toil is manual, repetitive, administrative, and automatable operational work that scales linearly with service size; SRE aims to cap toil at under 50% of an engineer's time.
Bonne réponse : BTo uncover systemic and technical root causes without assigning individual fault, implementing preventative safeguards
Blameless postmortems assume well-intentioned staff make mistakes within flawed systems; they focus on systemic causes to prevent recurrence without punishing individuals.
Bonne réponse : AComplex distributed systems have too many moving parts to prevent all failures; fast detection and recovery minimize user impact more effectively
In large distributed systems, component failures are an inevitability; investing in rapid mitigation, observability, and rollback (MTTR) preserves user experience better than trying to achieve zero failures.
Bonne réponse : BIt stops upstream callers from continuing to hammer the struggling service, preventing cascading failure across the architecture
A circuit breaker trips when failure rates rise, immediately returning errors or fallbacks to callers without hitting the downstream service, giving it space to recover.
Bonne réponse : BHolding ultimate operational authority, directing response logistics, delegating tasks, and maintaining focus across the team
The Incident Commander leads the incident response, delegating roles (investigators, communications), coordinating decisions, and ensuring the team stays organized without getting hands-on in the code.
Bonne réponse : BEngineers becoming desensitized to frequent, non-actionable notifications, leading to missed or ignored critical alerts
Alert fatigue happens when engineers are bombarded with non-actionable or false alerts; they become desensitized and may miss or delay responding to genuine outages.
Bonne réponse : BHow full a service or resource is, tracking constrained components like memory, CPU, or pool capacity
Saturation measures system fullness—the fraction of constrained resources in use (e.g., CPU, memory, database pool usage, disk I/O queue depths).
Bonne réponse : BAverages obscure tail latency outliers, masking significant performance degradation experienced by substantial user subsets
Averages hide extreme values; an average latency of 100ms could conceal the fact that the 99th percentile of users is waiting five seconds for their requests.
Bonne réponse : BProgressively doubling retry delays while adding random variance to prevent retrying clients from clumping into synchronized waves
Exponential backoff doubles wait times between successive retries, while jitter introduces random noise to prevent retrying clients from hammering the server in synchronized lockstep.
Bonne réponse : BStep-by-step procedures and diagnostics designed to help on-call engineers triage, troubleshoot, and mitigate specific system alerts
A runbook gives on-call engineers clear, actionable instructions, diagnostic steps, and mitigation commands to resolve specific alerts quickly under stressful conditions.
Bonne réponse : BA structured exercise where teams intentionally trigger controlled production failures to validate system resilience and team response readiness
A GameDay is a scheduled, coordinated drill where engineers simulate real-world failure modes to observe system behavior and validate incident response procedures.
Bonne réponse : BThe ability of a system to maintain core operations by disabling non-critical features during outages or resource exhaustion
Graceful degradation ensures that when components fail, the system sheds non-essential features (e.g., hiding personalized recommendations) while keeping core functionality working.