RFC 6593

Giocare a nascondino?…

In today’s domains, there are services that, by choice, prefer to not
be advertised and to cloak themselves with a shroud of anonymity.
However, protocols do not address the needs of these services. To
solve this, we propose a new paradigm of service hide-and-go-seek for
services that do not want to be discovered. A client may be looking
for a service, but an apathetic, playful, overwhelmed, or shy service
might prefer a hide or hint engagement, instead of directly showing
itself.

via RFC 6593