While researching some Active Directory questions the other day, I came across this Technet page that describes how the guts of the Active Directory data store actually function, how the data store fits into the overall architecture of Active Directory and a complete break-down of the processes and protocols that glue it to the other pieces of Active Directory, such as the File Replication Service (FRS).

This may be review for some of you but for others it may be a nice reference source.