There are two options for Active Directory integration. The first provides the most flexibility in managing roles and devices but requires Dell specific extensions to the schema, hence it's name "Extended Schema" http://support.dell.com/support/edocs/software/smdrac3/drac5/145/en/ug/racugc6.htm#wp42708 Also a good overview of it in Power Solutions http://www.dell.com/downloads/global/power/ps4q04-20040123-McGary.pdf. The simpler approach that uses Active Directory groups without schema changes is called "Standard Schema" and is written up in the User Guide at http://support.dell.com/support/edocs/software/smdrac3/drac5/145/en/ug/racugc6.htm#wp63374. RADIUS is not supported.

Roger, these docs should give me a good start. Does each DRAC need to have a new certificate that is obtained from the internal CA?

Not necessarily. There are two different communications channels, each with it's own set of options. When you browse to a newly installed DRAC you'll get a "Security Alert" pop up saying "The name on the security certificate is invalid or does not match the name of the site". Creating and installing a certificate from the internal CA would make this message go away. Really your choice from an experience point of view. Next, assuming you've configured and enabled Active Directory when you enter your username and password the DRAC will become a client and make a request to the Active Directory server with those credentials. For a secure connection on this channel, the DRAC's original design required a domain forrest root CA certifcate so that it could validate the authenticity of the AD server. With the newest iDRAC6 there is however an option to trust, i.e. not do this check http://support.dell.com/support/edocs/software/smdrac3/idrac/idrac10mono/en/ug/html/racugc7.htm#wp71022, step 6.