iChat configuration and its behavior
This is the behavior prior to AOS 6.4.3, iChat clients send infrequent periodic query (once every 60 minutes). If a new iChat client logs in, they will not see that client until they send the query to the controller. AirGroup sends unicast response to the new client about existing iChat clients in the network. But existing clients do not get any update from the controller regarding the new iChat user arrival.
Moving from 6.4.3 it uses mDNS “response packet ” to announce a user arrival. A new user entry will not reach the other existing users if the announcement (response) packet is not multicast
The existing users will get to know about the new user only when they send the periodic query which is less frequent.
With AOS v6.4.3, controller sends multicast packets to all the iChat clients, so existing clients know about the new iChat client arrival and it propagates the iChat response packet from the controller as multicast.This ensures that existing users can see the new user logs in.