Administering Windows Server Hybrid Core Infrastructure (AZ-800) Practice

The trust relationship that is automatically established between a parent domain and its child domain is a parent and child two-way transitive trust. This type of trust allows users in the parent domain to access resources in the child domain and vice versa. The transitive nature means that if there is a trust relationship between the parent domain and the child domain, and if the child domain has a trust relationship with another domain, users in the parent domain can also access resources in that other trusted domain.

This automatic trust relationship simplifies the management of security and resource access across the hierarchy of domains. It provides seamless authentication between the domains, allowing for efficient resource sharing and user access without the need for additional configuration steps to establish trust.

Other trust types, such as tree-root trusts or forest trusts, serve different purposes. Tree-root trust is established when a new root domain is added to a forest, while forest trusts enable resource sharing and security principals between two separate Active Directory forests. External trusts are used to connect domains in different forests that do not have a direct trust relationship, generally for specific scenarios involving non-Windows domains or legacy systems.