Transitive trust

The trust relationship that inherently exists between Windows 2000 and/or Windows Server 2003 domains in a domain tree or forest, or between trees in a forest, or that can exist between forests. When a domain joins an existing forest or domain tree, a transitive trust is automatically established. Transitive trusts are always two-way relationships. This series of trusts, between parent and child domains in a domain tree and between root domains of domain trees in a forest, allows all domains in a forest to trust each other for the purposes of authentication. For example, if domain A trusts domain B and domain B trusts domain C, then domain A trusts domain C.