[moandcompany]

"Zonal" relates to the concept of "availability zones" which are the next-smallest unit below a (physical) "region."

Most instances of a cloud ___ created in a region are allocated and exist at the zonal level (i.e. a specific zone of a region).

A physical "region" usually consists of three or more availability zones, and each zone is physically separated from other zones, limiting the potential for foreseeable disaster events from affecting multiple zones simultaneously. Zones are close enough networking-wise to have high throughput and low latency interconnection, but not as fast as same-rack, same-cluster communications.

Systems requiring high availability (or replication) generally attain this by placing instances (or replicas) in multiple availability zones.

Systems requiring high-availability generally start with multi-zone replication, and Systems with even higher availability requirements may use multi-region replication, which comes at greater cost.