> On Aug 13, 2018, at 6:26 PM, John C Klensin <john-ietf@xxxxxxx> wrote: > > the string 128.0.0.1, is a domain name Yes, it is the presentation form of the domain name whose list of labels is: "128", "0", "0", "1". There is of course no TLD named "1", so this domain is not registered, and it would also not be a usable hostname, since many libraries would treat it as a literal IP address instead. And yet it is still a domain name. Indeed in a non-public network, I'm free to provision a ".1" TLD, and even create hosts as sub-domains of this name: example.128.0.0.1. IN A 192.0.2.1 perhaps making "128.0.0.1" an empty non-terminal. -- Viktor.
