[THIN] OT: determine domain functional level history

So I'm pulling the lastLogonTimeStamp attribute for user accounts via script
as part of a clenaup effort, and for many accounts there's no entry. Since
this attribute is only available for a windows 2003 functional level I'm
hypothsizing that these accounts simply haven't been logged onto since the
functional level was raised to 2003. Anyone know of where/how to query AD to
determine when that occurred, or if that info is even stored?

Other related posts: