What makes a zone Read-Only? - BlueCat Address Manager - 8.3.2

Address Manager Administration Guide

BlueCat Address Manager

The mode of the Master server, or AD-integrated elect determines whether the zone is Read-Only or Read-Write.

For example, if the server with the master role is in Read-Only mode and one or more of the servers with the slave roles are in Read-Write mode, the zone is still considered to be a Read-Only zone.