KDC
The Key Distribution Centers (KDCs) issue Kerberos tickets. Each KDC contains a copy of the Kerberos database. The master KDC
contains the master copy of the database, which it propagates to the slave KDCs
at regular intervals. All database changes (such as password changes) are made
on the master KDC. Slave KDCs provide Kerberos ticket-granting services, but not
database access. This ability allows clients to continue to obtain tickets
when the master KDC is unavailable.