Hi,
Sometimes, it is no easy to found the IP address of IAP... (no closed IAP or no documentation about IP configuration...)
There is a easy method for found the IP Address of IAP.
You need a lasted build of Wireshark (> 1.11.3 available here, will be available in next major release 1.12 in may/june 2014).
Set a laptop in some network (vlan) like IAP and launch capture :
set aruba_iap display filter in Wireshark
And i will display the list of IAP will be broadcast in the network with the IP of IAP :
Now, launch your favorite browser and launch a connexion to the IP found by Wireshark ! :-)