Create a new group, use dynamic population, specify Windows Computer > NetBIOS Domain Name > Does not match Regular Expression. Then specify each domain as required.
Example regex:
(domain1.*|domain2.*|domain3.*)
Use a site like https://regexper.com/ to check your regex. Example:
You may also need to add the case insensitive prefix:
(?i)(domain1.*|domain2.*|domain3.*)
I’ve used wildcards (.*), but you can specify them as full domain names, or use the wildcards differently to cover a broader naming convention. Regex is incredibly versatile, and there’s plenty of documentation online for it.