So, it appears that the iDRAC facilities use the physical interface on the CMC, not on any of the A1-C2 networking modules. Even though that interface was plugged into our public-IP network (along with our A1 network interface), I was able to avoid consuming public IP's with our iDRAC interfaces by issuing private IP aliases to the A1 interfaces on our blades.
I've got a PowerEdge 1000e with a bunch of blades plugged into it and it also has *six* M6220 ethernet switches on it. I've configured each server so that it has a distinct IP on each switch from the following subnets: A1 - public IPs (111.222.333.*, for example) A2 - private IP's (192.168.10.*) B1 - private IP's (192.168.20.*) B2 - private IP's (192.168.30.*) C1 - private IP's (192.168.40.*) C2 - private IP's (192.168.50.*) Each server A can ping any other server B on any of B's six IP's (so they can all "see" each other on all of the switch interfaces.  Additionally, the CMC interface has a public IP, and it's plugged into switch A1 (the public IP switch). Now, when I want to use the iDRAC interface (to access, say, the console of one of the servers), it works *fine* (meaning that I'm able to user a browser on one of the blades to access the iDRAC console of any *other* blade) if I assign public IP's to the iDRAC interfaces. However, if I assign an address from any of the *private* subnets (because my public IP's are scarce), I'm not able to reach the iDRAC console. Are the iDRAC interfaces only tied to A1 or something, or is there a reason why I shouldn't be able to reach them via the other switches? 
What network interface is iDRAC tied to on a PowerEdge 1000e?