last log on active directory

To understand the theory,

http://blogs.technet.com/askds/archive/2009/04/15/the-lastlogontimestamp-attribute-what-it-was-designed-for-and-how-it-works.aspx

So this attribute wont give the actual realtime information.
For real time information, you should check for the logon events on eventviewer on all DCs.

Cheerio
Shaba

You can get the different Logon reports with the following

Active Directory User Logon Reports
http://www.manageengine.com/products/ad-manager/windows-active-directory-logon-reports.html