Several resources are available to help you deepen your understanding of directory services and the technologies behind Open Directory. These are:
Essential Mac OS X Panther Server Administration, by Michael Bartosh and Ryan Fass (O’Reilly Media, Inc., 2005)
Mac OS X Server Open Directory Administration, by Apple Computer; available at http://www.apple.com/macosx/server.
LDAP System Administration, by Gerald Carter (O’Reilly Media, Inc., 2003)
Kerberos: The Definitive Guide, by Jason Garman (O’Reilly Media, Inc., 2003)
Active Directory, Second Edition, by Robbie Allen, et al. (O’Reilly Media, Inc., 2003)
Also, you may want to refer to the following manpages:
DirectoryService
netinfo
dscl
nicl
nidump
niload
fsck