Full_Name: Quanah Gibson-Mount Version: 2.4.44 OS: N/A URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (47.208.148.239)
The man page for serverID says:
serverID <integer> [<URL>] Specify an integer ID from 0 to 4095 for this server (limited to 3 hexadecimal digits). The ID may also be specified as a hexadecimal ID by prefixing the value with "0x". These IDs are required when using multimaster replication and each master must have a unique ID. Note that this requirement also applies to separate masters contributing to a glued set of databases. If the URL is provided, this directive may be specified multiple times, providing a complete list of participating servers and their IDs. The fully qualified hostname of each server should be used in the supplied URLs. The IDs are used in the "replica id" field of all CSNs generated by the specified server. The default value is zero. Example:
serverID 1
However, it does not specifically note that serverID 0 is reserved for single master only, and that in MMR & Mirror mode configurations, serverIDs must be 1 and higher.
The admin guide likely needs similar updating.