Environment : This article applies to Aruba Instant Access points running Instant OS.
Answer : A bunch of IAPs deployed in a same L2/L3 network form a cluster. The cluster consists of IAPs in two roles: Virtual Controller (VC) and non-VC. The first IAP that comes up in the cluster gets self-elected as the VC. All subsequent IAPs that come up discover the VC and update their configuration and firmware based on information from the VC.
To form a cluster, IAPs of any model should belong to same regulatory domain. Consider a cluster of 5 access points belongs to the regulatory domain "US" and if we try to bring up a 6th access point who's regulatory domain is "RW"(Rest of the World), it will fail to join the cluster. The radio light of 6th IAP will lit up red and from "ap log all" executed on VC, we could see the error "AP regulatory domain don't match Master"
Output from WebUI:
Output from CLI: