Active Directory stores users’ last logon dates in
lastLogon attribute and last successful password set dates in
pwdLastSet attribute. You may think that it’s as easy as running an LDAP query to get these values. Unfortunately, it’s not that simple.
If you check these values in ADSI Edit tool, you will see a well formatted timestamp. However, if you double click it, you will see a long integer. This is the value your .NET code will receive through an LDAP query. Active Directory returns dates as
Int64 data type.
In order to convert Active Directory’s
Int64 timestamps to .NET’s DateTime format, use the following code line.
DateTime lastLogon = DateTime.FromFileTime((long)oSearchResult.Properties["lastLogon"]);