Active Directory uses rules called Trusts to allow users in a given domain to access resources in another domain. There are many different types of trust rules that grant varying levels of access and permissions to users. Trusts can be one-way or two-way. In a one-way trust, users from Domain A can access Domain B, but users from Domain B cannot access Domain A. Trusts can be transitive or intransitive. A transitive trust can be extended to more than two domains in the forest, while an intransitive trust is a one-way trust that exists between only two domains. A forest trust applies to the entire forest, is characteristically transitive and may be one-way or two-way. The default boundary for forest trusts is set by the network administrator and will be automatically applied for all newly created domains.