The last time the user logged on. This value is stored as a large integer that represents the number of 100-nanosecond intervals since January 1, 1601 (UTC). A value of zero means that the last logon time is unknown.
The high part of this large integer corresponds to the dwHighDateTime member of the FILETIME structure and the low part corresponds to the dwLowDateTime member of the FILETIME structure.
This attribute is not replicated and is maintained separately on each domain controller in the domain. To get an accurate value for the user's last logon in the domain, the Last-Logon attribute for the user must be retrieved from every domain controller in the domain. The largest value that is retrieved is the true last logon time for that user.