A zonal incident is a failure that affects resources inside one availability zone or one data-center segment. In cloud systems, zones are meant to be isolated failure domains, so a problem in one zone should not automatically take down the whole region. Typical causes include power loss, network faults, storage failure, misconfiguration, or physical damage to a facility.
This term matters in cyber security because resilience is part of defense. Attackers may try to trigger or exploit zonal incidents to create denial of service, distract responders, or force failover paths that expose weak dependencies. Defenders use zoning, replication, and automated failover to keep the blast radius small. When a zonal incident is handled well, only the affected zone is degraded; when it is handled poorly, shared identity, routing, or messaging services can spread the outage to customer-facing systems.