Quick question...
Why are you putting these into the CMDB? Usually AD "objects" would be imported into the associated tables in ServiceNow:
- Users -> Users
- Groups (or OUs) -> Groups
The forest is just an abstract organization. CMDB is usually reserved for Infrastructure components and their associated configuration, as well as Business Services and Service Offerings. The only AD "objects" that would potentially be imported would be Computers, but there are much better ways (and more complete ways) than importing via AD (using SCCM would be a good one).
Your first link is regarding discovery of Domain Controllers, this can be accomplished through an SCCM integration, or via ServiceNow Discovery.
Your second link is to documentation on Service Mapping, which if you own it, would map Business Services down into your CMDB.
Can you describe your use case? What are you trying to achieve?
-Rob
