Inverse

Master

A Master DNS defines one or more zone files for which this DNS is Authoritative ('type master')

Slave

A Slave DNS gets its zone data using a zone transfer operation (typically from a zone master) and it will respond as authoritative for those zones for which it is defined to be a 'slave' and for which it has a currently valid zone configuration. It is impossible to determine from a query result that it came from a zone master or slave.