[dns-operations] about the underline in hostname

[Mark Andrews]

In message <538815D5.8000609 at ncartron.org>, Nicolas CARTRON writes:
> On 29/05/2014 10:24, hua peng wrote:
> > I found this is a valid RR:
> >
> > _spf.yandex.ru.         2768    IN      TXT     "v=spf1
> > include:_spf-ipv4.yandex.ru include:_spf-ipv6.yandex.ru ~all"
> >
> >
> > But for A, CNAME, AAAA etc, the underline in hostname is invalid.
> > Does this make a confusion?
> >
> > Thanks.
> Nope, see RFC 2872 for instance.

I think you meant RFC 2181 but that does not change what is legal
in a hostname.  You can store hostnames in the DNS.  You can store
other things in the DNS.  This is like writing on paper.  RFC 2181
is about what are legal keys in the DNS.

		hostname != domain name

_spf.yandex.ru is not a legal hostname whether it is written on
paper, in crayon on the driveway, in chalk on a blackboard or when
it is stored in the DNS.

_spf.yandex.ru is not a legal hostname alias for another hostname.

Mark

> -- 
> Nicolas.
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-- 
Mark Andrews, ISC
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PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org