The msDS-SiteName attribute exists on AD DS but not on AD LDS.

Let TO be the object on which msDS-SiteName is being read. If TO is an nTDSDSA object or a server object, then TO!msDS-SiteName is equal to the value of the RDN of the site object under which TO is located. For example, given a TO that is an nTDSDSA object with the DN "CN=NTDS Settings, CN=TESTDC-01, CN=Servers, CN=Default-First-Site-Name, CN=Sites, CN=Configuration, DC=fabrikam, DC=com", the value of TO!msDS-SiteName is "Default-First-Site-Name".

If TO is a computer object, then let TS be the server object named by TO!serverReferenceBL. TO!msDS-SiteName equals TS!msDS-SiteName.

If TO is neither a computer, server, nor nTDSDSA object, then TO!msDS-SiteName is not present.