An all-too-quick 40 minutes? At a user/usage level? There's a LOT to choose from, but as a great start, try RFC2504. http://www.ietf.org/rfc/rfc2504.txt?number=2504 Pick and choose as appropriate to your needs. We tried to make it very useful as a reference for the generic user. You can even hand out copies if you like. For a bit more detail, and as a good read in case you get asked some lower-level questions, try RFC 2196, more specifically targeted for IT folks, and "Middle Managers" who have to at least be exposed to the concepts. http://www.ietf.org/rfc/rfc2196.txt?number=2196 Cheers, Steve PS(don't let the fact that these are TEN years old fool you, most of these concerns are still quite current, most companies (read: those of popular OSes) don't exactly *want* people to understand the why's because they start to question the why-not (yet)s. If you found any of this useful, or not, just reply here, Most if not all those email addresses are defunct at this point -- we've moved onto and into other things).