Tree-root trust confusion

Solution 1:

According to This technet article, the default intra-tree trust architecture is rooted and transitive, not full-mesh.

My trusty copy of Windows 2000 Active Directory by Lowe-Norris does contain some confusing language that could be misconstrued as implying that a full-mesh trust system is set up, Maybe that's where your confusion is coming from?

Solution 2:

An AD trust is represented in AD by a TDO (trustedDomain object). If you view the domain partition in ADSIEdit you'll see that a TDO exists for a child domain's direct parent domain and it's child domains (if they exist). You won't see a TDO for any shortcut trusts because they're not automatically created between child domains. The trust path is "vertical".