AD Group Discovery should not write DDR for invalid records
When System Discovery finds an object that seems invalid, currently it won`t be imported (which is good).
ERROR: System <systemname> is a unsupported operating system, unsupported version, or malformed AD entry. Reported system type is: ().
However if the same object has an AD Group Membership and AD Group Discovery finds it, it won't check if it is valid, but write the DDR and create the object record in SCCM DB.
Please change AD Group Discovery so it validates new objects too.
seb cerazy commented
It indeed makes NO SENSE!
And make it merge records based on netbios name again (feature removed in CM2012 SP1 and has since then casused issuses for at least 500 000 clients in my country alone).
alternative to this is to merge on FQDN.