What are zones in sharding?
Zone is a grouping of documents based on ranges of shard key values for a given sharded collection. zones are logical groupings of shards based on specific criteria, such as geographical location or data type. Each shard in the sharded cluster can be in one or more zones. In a balanced cluster, MongoDB directs reads and writes for a zone only to those shards inside that zone. See the Zones manual page for more information.
Geographic Zones: Data is distributed into shards based on regions, ensuring users in Asia primarily interact with servers in Asia, minimizing access delays.
Functional Zones: Shards are grouped based on application-specific logic, such as separating user data from transaction data.