# Fault Tolerance in Central Administration

Central Administration uses the same JSON configuration file to manage both servers in a fault tolerant pair. Primary and secondary server roles are determined when the servers are started.

All but two configuration settings are shared by both EMS servers: the `listen` and `ft_active` parameters are configured separately.

- The primary server, if elected active, listens for client connection on ports defined in the main Server Properties page, in the Primary Listens section. If elected standby, it listens for the secondary server on the Secondary Listens URL that is flagged using the FT Active radio button on the Fault Tolerance properties page.
- Conversely, the secondary server, if elected standby, listens for the primary server using the Primary Listens URL that is flagged with the FT Active radio button on the main Server Properties page. If elected active, it listens for client connections using the Secondary Listen URLs defined on the Fault Tolerance page.

For more information on Central Administration, see TIBCO Enterprise Message Service Central Administration.

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