Debugging

Production is degraded and "nothing changed". Where do you start?

Whether the candidate treats "nothing changed" as a claim to be tested, and whether they have an ordered search rather than a hunch.

The situation behind the question

At 09:03 a service's p99 latency triples and stays there. The last deploy was six days ago. The team has dashboards for the service but no deploy or config annotations, and the infrastructure repository is applied by a nightly job.