Not sure, what you with multi-home. I didn’t setup the network structure + Openfire, but our system admins told us, that when you are in the company’s intranet you can reach it ONLY via an internal IP address and NOT the external one. I don’t know why this is, but this is how it is configured.
If you are in the internet, e.g. at home, you obviously cannot reach it via the internal IP, but only via an external one.
So, you basically have 2 IP addresses pointing to the same server, but depending on where you are (intranet vs internet), then one will work and the other not.
So I thought somehow one DNS server which returns both IP addresses and is reachable from external and internal network may solve this problem, so that collegues don’t need to switch between server settings.
But maybe I am misunderstanding things. I am not very familiar with networking and DNS resolution.