I'm working on a very non-profit website (many are).  A question/statement came up about using AD with DNN, how does it affect licensing?  According to the person who brought  up the question, the question is based on last time the person checked with Microsoft : 

For most directory services, it is the case that anytime you use a resource on the server you required a license.  Doing an authentication is using a resource, hence a need to have a Client Access License (CAL) for everyone that will be logging in to the site.  (http://www.microsoft.com/resources/sam/lic_cal.mspx)

Granted, the authenitcation will only be useful to those who are actually already logged on to the site from the LAN.  I don't know that it is coded such that every person who tries to login to the DNN site outside of the LAN actually uses AD server resources.

There must be consultants who have already had to address the question/issue of how using DNN affects Client Access Licensing?  Opinions, please?  Thanks.

if you are using microsoft active directory for authentication, then you will need to purchase a CAL.Not sure if it is by device or user, you gotta confirm with Microsoft sales person. Not only that, you also need to purchase Windows Server Internet Connector License if you are hosting your DNN on the Internet.