synchronizing database files of a central node with database files of a local node in which the central node is coupled to the local node via a communication link . the communication link performance being continuously monitored via a periodic signal sent back and forth between the central node and local node . information indicative of the files of the central database are integrated with the monitoring signal portion sent from the central node to the local node and a determination is made whether the files integrated with the monitoring signal corresponds with files of the local database via indications in the monitoring signal portion returned from the local node .