Some of the entries in the xfer logs are denoted INCOMPLETE. What does this mean?
The INCOMPLETE keyword denotes a transfer that definitely did not finish (for example, NcFTPd received a disconnection notification after only sending 30,000 bytes of a 200,000 byte download) or that the file was reputedly transferred in full, but the remote FTP client did not acknowledge that the transfer concluded successfully. The first case is a simpler problem to understand; it indicates that the remote user disconnected before the transfer completed, or that the connection to the user was lost due to network problems. The second case is a bit more difficult to explain. By default, NcFTPd requires implicit acknowledgment of downloads (and uploads) before creating a log entry. The remote user implicitly acknowledges a successful download by doing something else in the FTP session, such as changing to another directory or downloading another file, or even issuing a QUIT command to close the session. This allows NcFTPd to differentiate between transfers which were definitely received
