Kerberos Realms
Each administrative domain will have its own Kerberos database, which
contains information about the users and services for that particular
site or administrative domain. This administrative domain is the
Kerberos realm.
Each Kerberos realm will have at least one Kerberos server, where the
master Kerberos database for that site or administrative domain is
stored. A Kerberos realm may also have one or more slave servers,
which have read-only copies of the Kerberos database that are
periodically propagated from the master server. For more details on how
this is done, see the "Set Up the Slave KDCs for Database Propagation"
and "Propagate the Database to Each Slave KDC" sections of the
Kerberos V5 Installation Guide.