Technical interview guide

Capacity Planning & Load Testing

Knowing how much traffic a system can take before it does, through modeling and deliberate load testing.

Read: 28 min
Practice MCQs: 25
Interview QA: 25
Edition: v4
Editorial status: Reviewed
Relevant for: DevOps EngineerForward Deployed Engineer (FDE)Site Reliability Engineer

Scope: Google SRE, Kubernetes, OpenTelemetry, Prometheus, k6, JMeter, PostgreSQL, and IETF guidance 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: 2026-10-05 · Reviewed: 2026-10-03

QA-1

Build a capacity plan for a fast-growing API.

QA-2

Design a representative load model for an e-commerce event.

QA-3

Plan a safe production load test.

QA-4

Find a system's real bottleneck from a load test.

QA-5

Test autoscaling for a sudden traffic spike.

QA-6

Choose headroom for a critical service.

QA-7

Explain and prevent coordinated omission.

QA-8

Design a soak test for a stateful service.

QA-9

Validate graceful degradation and load shedding.

QA-10

Capacity-test a database-backed service.

QA-11

Investigate a latency cliff as concurrency rises.

QA-12

Create performance regression gates for CI.

QA-13

Capacity-plan a third-party dependency with a hard quota.

QA-14

Plan capacity for asynchronous queues and workers.

QA-15

Interpret p99 latency responsibly in a capacity report.

QA-16

Run a capacity test with one zone unavailable.

QA-17

Evaluate whether caching improved useful capacity.

QA-18

How do you distinguish between application-level bottlenecks and infrastructure or network saturation during a distributed stress test?

QA-19

Capacity-plan a service before a major product launch.

QA-20

Test retry behavior under overload.

QA-21

Model capacity when request costs vary widely.

QA-22

Validate the load-test generator and result pipeline.

QA-23

Turn a failed load test into an engineering plan.

QA-24

Govern capacity and load testing as a continuous program.

QA-25