Forest - forests define the trust relationships between different domains.
Forest Root Domain – The first domain in a forest.
Tree Root Domain – The top-level domain in a domain tree.
Domain Tree - a tree root domain and a collection of one or more child domains.  Child domains inherit the parent domain, hence forming a tree.
Top-level Domain – Also called the parent domain. See tree root domain.
Child Domain – Second-level domains.  They sit directly under the top-level domain.

Some other quick notes:
– Within a domain tree, all domains have 2-way transitive trusts, share a common schema and share a common global catalog.
– Replication describes the rules that govern the updating of the AD database across domain controllers.

That’s it, pretty simple really.  Diagram coming soon – this is even simpler with the help of a diagram.

Originally posted 2009-09-18 03:00:20.