How did I fix the «epmd error for host» / «badarg (unknown POSIX error)» failure on a RabbitMQ start?

RabbitMQ
1

The contents of /etc/hostname was 194.39.164.132.srvlist.ukfast.net.
This "194" at the start caused the error.
I replaced the /etc/hostname contents with the real domain name.

stackoverflow.com/a/30608959