[dns-operations] TLD(s) for private use

[James Stevens]

On 11/09/17 14:52, Suzanne Woolf wrote:
> 
> On Sep 9, 2017, at 2:29 PM, "John Levine" <johnl at taugh.com> wrote:
> 
>> In article <97ad36f6-4b83-8db9-1bab-e88466988e77 at jrcs.co.uk> you
>> write:
>>> I've not yet seen any response as to why a prefix that includes
>>> one or more UNDERSCORE wouldn't be a viable solution - e.g.
>>> "zz__" - or even all "[LETTER][LETTER]__" - where "XN__" could be
>>> IDN?
>> 
>> Because you can't use underscores in hostnames.  Even if it's not
>> on the public Internet, you will run into too much software that 
>> correctly refuses hostnames that aren't ldh.
> 
> Indeed, I'd regard LDH compliance as essential. See also
> https://www.icann.org/resources/pages/universal-acceptance-2012-02-25-en;
> the "universal acceptance" problem, as stated, is rather wider than
> the requirement here, because we were talking about locally scoped
> names-- but assuming "lowest common denominator" software and
> operational practice is pretty important if you're trying to draft a
> solution that works for even most of the people, most of the time.

It would be impossible to disagree - just interesting to see that
underscore in public names is astonishingly common - like SRV records,
so I assumed underscore was reasonably well supported.

https://en.wikipedia.org/wiki/SRV_record
https://tools.ietf.org/html/rfc2782

And PSL requires you add "_psl" to zones

https://publicsuffix.org/


...etc...



James