A. Windows NT 4.0 trust relationships aren’t transitive. Therefore, if domain2 (e.g., Marketing, in the Figure) trusts domain1 (Sales), and domain3 (Development) trusts domain2 (Marketing), domain3 (Development) doesn’t trust domain1 (Sales).
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In Windows 2000, the trust relationships that connect members of a tree or forest are two-way, transitive Kerberos trusts. Thus, all the domains in a tree implicitly trust all the other domains in the tree or forest. Because trusts occur automatically when a domain joins a tree, time-consuming trust administration is unnecessary.
Kerberos is Win2K’s primary security protocol. Kerberos verifies a user’s identity and a session’s data integrity. Each domain controller (DC) has Kerberos services on it, and every Win2K workstation and server has a Kerberos client. A user's initial Kerberos authentication gives the user one logon session to enterprise resources. Kerberos isn’t a Microsoft protocol but is based on MIT’s Kerberos 5.0. For more information about Kerberos, see the Internet Engineering Task Force (IETF) Requests For Comments (RFC) 1510, The Kerberos Version 5 GSS-API Mechanism.