From REM Publications:
The Network Time Client connects to a time server through the Internet, gets the current time, and adjusts the clock of your PC. This software uses the DAYTIME protocol and is RFC-867 compliant. Usually, time servers are synchronized using an atomic clock. However, the DAYTIME protocol doesn't support the transfer of the exact time (down to 1 millisecond) but your system time should be at least within 500ms (half a second) of the 'real' atomic time. From now on, e-mails, Office documents, log entries will have the exact time and not just an 'approximative' value.