Trust relationships are defined in only one direction. In the previous example, just because the London domain trusts the Topeka domain does not mean that the Topeka domain trusts the London domain. For a two-way trust relationship, each domain must be configured to trust the other.
Trust relationships are not transitive. For example, if the London domain trusts the Topeka domain and the Topeka domain trusts the Melbourne domain, that does not mean that the London domain trusts the Melbourne domain. For the London domain to trust the Melbourne domain, a trust relationship must be explicitly established.
Users and computers from the trusting domain have no special status on the trusted domain. The names of trusting domains do not appear in the From box of the Logon dialog box, nor do users from the trusting domain appear in the File Manager of computers in the trusted domain.