Availability and Resilience
Why every dependency fails eventually, and how to keep serving users anyway. You quantify availability with SLOs and error budgets, design redundancy and failover, and apply resilience patterns like circuit breakers, backed by observability.
This domain starts from an uncomfortable fact: at scale, something is always failing. You learn to measure availability the way operators do, set SLOs and spend error budgets deliberately, and build redundancy that survives a zone loss. The resilience topics then harden every call path with timeouts, retries, circuit breakers, and graceful degradation, all made visible through observability.