Each time you synchronize a local directory, the name, remote target, time, and status are recorded in an invisible file named ".syncdat".
In its default Peer mode, SyncDat compares the modification time of each file being synchronized to the recorded time of the last synchronization to decide whether or not that file has recently changed. If the file exists on both the local and remote systems, but only one version has recently changed, that version will be copied to the other side.
Likewise, if a file no longer exists on one side and has not changed since the last scan on the other side, the file will be deleted.
The ability of SyncDat to correctly determine when an event has occurred relative to the last scan depends entirely on the accuracy of the local and remote System Clocks.
If a file appears to have been modified on both sides since the last synchronization, then they are considered conflicting. If SyncDat is running interactively, it will ask how the conflict should be resolved. Otherwise conflicting files will be ignored.
SyncDat relies on information about the remote system to decide whether or not you have synchronized to it before. If you access the same remote directory using a different username, IP address, port number, or pathname, SyncDat may assume this to be a new synchronization.