FreePBX Firewall Question

So if I understand everything correctly if I go into “Connectivity > Firewall > Zones > Networks” and I have ANY hostname that is automatically updated from ANY carrier then the Firewall Module will scan that and automatically update my IP address for Trusted as soon as my IP is updated by the provider? (Providing I have something on my network telling the provider to update the changed IP address!) And it doesnt have to be a specific provider like Dyn?

Also what is the scan frequency?