If I recall it correctly, it's another "flavor" of
secondary zone; but while a secondary zone
holds a full copy of the zone records, the stub
one holds just the "glue" records, i.e. the records
related to the authoritative DNS servers for the
stub zone ... hope it's clear
Stub zone contains only three records: Start of authority (SOA), Name server
(NS) and the glue A resource records. No zone transfer between any
zones..Just a traffic controller!!