I have a number of guests who connect to our network for maybe only a couple of days at a time. They appear on lansweeper as WMI access denied. I then need to manually clear them down.
How can I stop any devices not listed in my active directory from being scanned or added to the DB?
You can prevent scanning of foreign computers by only scanning with Active Scanning (detailed description can be found here) and/or Scheduled computer scanning (detailed description here). Under Configuration\Scanning methods, section IP Address Range scanning, hit "No Windows" for all of your IP ranges and in section Workgroup Scanning do not enable Workgroup scanning.
You can prevent scanning of foreign computers by only scanning with Active Scanning (detailed description can be found here) and/or Scheduled computer scanning (detailed description here). Under Configuration\Scanning methods, section IP Address Range scanning, hit "No Windows" for all of your IP ranges and in section Workgroup Scanning do not enable Workgroup scanning.