An LDAP Roadmap & FAQ

A tutorial aid to navigating various LDAP and X.500 resources on the Internet

Under Construction   This is v2.0a -- a "beta" release -- it is still way under construction. You will find version 1.5, which may or may not be more up-to-date, HERE. Apologies for any confusion. 
Jeff Hodges, Editor/Compiler 
Principal, Kings Mountain Systems; and.. 

Principal Engineer, Oblix Inc

Selected by PC                                                                                          Webopaedia

Last updated: 21-Jan-2001
Version 2.0a 

Overall Contents:


So, for some reason or another you have to figure out more about this stuff variously called X.500, LDAP, "the Directory", the "White Pages Project", etc.....and you're very confused and can't figure out where to start, which documents are relevant to what aspects of this crazy stuff, which ones to read first, which ones provide an overview, where to get what software or anything else. Well, I've been there and done that and thought that I'd put together a kind of road map and high-level FAQ (Frequently Asked Questions) that points off to other Web sites and various docs and kinda provide a helping hand to getting started with this complex, but way-cool, Directory stuff.


X.500 is an overall model for Directory Services in the OSI world. The model encompasses the overall namespace and the protocol for querying and updating it. The protocol is known as "DAP" (Directory Access Protocol). DAP runs over the OSI network protocol stack -- that, combined with its very rich data model and operation set makes it quite "heavyweight". It is rather tough to implement a full-blown DAP client and have it "fit" on smaller computer systems. Thus, the folks at University of Michigan, with help from the ISODE Consortium, designed and developed...

LDAP, or "Lightweight Directory Access Protocol". LDAP is, like X.500, both an information model and a protocol for querying and manipulating it. LDAP's overall data and namesapce model is essentially that of X.500. The major difference is that the LDAP protocol itself is designed to run directly over the TCP/IP stack, and it lacks some of the more esoteric DAP protocol functions.

A major part of X.500 is that it defines a global directory structure. It is essentially a directory web in much the same way that http & html are used to define & implement the gobal hypertext web. Anyone with an X.500 or LDAP client may peruse the global directory just as they can use a web browser to peruse the global Web. Additionally, with the help of web<->X.500 gateways, you can use your favorite web browser to peruse both!

Note: Please help me out and let me know if you find any stale links in these pages or if you have any other feedback. Thanks, Jeff

The Roadmap Table of Contents

The following is an annotated list of pointers to information sources. Start at the begining if you're an X.500/LDAP/Directory newbie. Else, peruse the list and start whereever seems appropriate. Happy hunting...

An LDAP Frequently Asked Questions (FAQ) List

This is not the LDAP FAQ, it is an LDAP FAQ. I don't think there is "THE LDAP FAQ" (at the time of this writing) in the sense of "the" FAQs at the Usenet FAQ archive at This FAQ consists of the pointer below to Mark Wahl's LDAP FAQ (which is explicitly about the UMich LDAP release), plus questions that aren't covered in the aforementioned FAQ that I feel I can at least somewhat answer. I will try to add to this from time-to-time (no guarantees), but you can help...


Please do send me contributions and/or bug reports for these pages. I will list you on the contributors page if you wish. If I take a while to get back to you it is because I'm juggling various balls and tend to "batch up" things to do before tackling them, and also I get 100-200 email messages a day. I will try to at least send a "I received your message and will add it to the to do list " message when I receive something. Thanks, Jeff.

You may send your contributions/bug reports to the appropriate address:

Contributor's Page

Currency of Information and Links in these Roadmap webpages:

Please email me if you find any issues with links and/or the content of these pages. Thanks.

These pages are revised from time-to-time -- as are many documents, software, and race cars.


  • Ros Halevi and Jing-Chyi Chao html-ized Tim Howes' LDAP paper.
  • Thanks to Tim Howes, Mark Smith, Gordon Good, Mark Wahl, Steve Kille, Chris Apple, Chris Weider, Paul Hoffman, and a host of others for answering (and continuing to answer) my many questions.
  • Additional credits...

    The Attendant Fine Print:

    This document doesnot purport to be the last, best, or most recent word on LDAP or developments in the directory community. THIS DOCUMENT IS UPDATED AND OTHERWISE MAINTAINED ON A BEST-EFFORTS BASIS. This information is provided AS IS, with no guaranties at all. It is the readers' responsibility to keep themselves up-to-date and aware of developments by whatever means they have available. I trust the pointers and info here help in that effort.

    © 1996-2000 Jeff Hodges, All Rights Reserved