Potential failures include database unavailability, cache stampedes, code collisions, analytics backlog, malicious destinations, and accidental deletion. Define behavior for each. For example, if analytics is down, redirecting may continue while events are buffered or dropped according to product requirements.

At higher scale, add read replicas or partition mappings by code hash if measured bottlenecks justify them. Use CDN or edge caching only when revocation and freshness requirements permit. Add regional replicas and a recovery plan if global availability becomes necessary.

Validate with load tests covering hot codes, random codes, expired links, disabled links, and cache misses. Monitor redirect p95/p99 latency, error ratio, cache hit rate, database saturation, queue age, abuse rates, and collision retries.