Technical interview guide

SLIs, SLOs & Error Budgets

The vocabulary reliability is measured in, and how an error budget turns 'be reliable' into a concrete number.

Read: 30 min
Practice MCQs: 25
Interview QA: 25
Edition: v4
Editorial status: Reviewed
Relevant for: AI EngineerDevOps EngineerForward Deployed Engineer (FDE)Site Reliability Engineer

Scope: Google SRE guidance, Prometheus, and OpenSLO current 2026-08-31.

Interview QA

Treat each question like a live interview question: answer out loud first (structure, assumptions, tradeoffs), then open the model answer to spot gaps and rehearse a tighter follow-up.

Curated: 2026-10-05 · Written: 2026-09-11 · Reviewed: 2026-10-03

QA-1

Define an SLI, SLO, SLA, and error budget with one coherent example.

QA-2

Design availability and latency SLOs for an API.

QA-3

Choose the measurement point for a user-facing SLI.

QA-4

Define the numerator and denominator for a request-based SLI.

QA-5

Set an SLO target without copying current availability.

QA-6

Calculate and explain an error budget correctly.

QA-7

Design multiwindow burn-rate alerts for an SLO.

QA-8

Handle SLO alerting for a low-traffic service.

QA-9

Write an error-budget policy for a product team.

QA-10

Decide whether an incident should consume error budget.

QA-11

Choose rolling versus calendar SLO windows.

QA-12

Prevent aggregate SLOs from hiding cohort harm.

QA-13

Compose end-to-end reliability from dependency objectives.

QA-14

Design SLOs for an asynchronous data pipeline.

QA-15

Instrument a latency SLO with Prometheus histograms.

QA-16

Validate an SLO implementation before using it for policy.

QA-17

Migrate an existing SLO definition without rewriting history.

QA-18

Respond when an error budget is exhausted.

QA-19

Handle delayed or corrected telemetry in SLO reporting.

QA-20

Audit SLO exclusions for gaming and drift.

QA-21

Use SLOs during canary and progressive delivery.

QA-22

Design privacy-conscious client-side SLI telemetry.

QA-23

Capacity-test an SLO measurement and alerting pipeline.

QA-24

Review SLOs after an incident that did not breach them.

QA-25