Zeroconf assumes that all of the interfaces passed into the library via Zeroconf(interfaces=[<address_0>, <address_1>,...] are able to be bound to. This isn't always the case, for example in a sandboxed environment such as iOS.

In iOS, you are able to bind a socket to 127.0.0.1:5353 but you aren't able to bind to the en0 and pdp_ip0 interfaces on port 5353 because the system daemon is already bound to that. There needs to be a way to configure which addresses are apart of the multicast group that zeroconf builds in.