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Re: [DNSOP] Minor editorial change to draft-ietf-dnsop-sutld-ps

2017-07-06 19:44:59

In message <901C29488D8446E4176CF83E@PSB>, John C Klensin writes:

--On Thursday, July 6, 2017 09:11 +1000 Mark Andrews
<marka(_at_)isc(_dot_)org> wrote:

And the actual presentation limit for LDH with DNS is 253
(encodes as 255 octets on the wire).  Remember URI names do
not have a final period and the each label has length octet
when encoded as a DNS name and the name is terminated by the
root label (0x00) in DNS wire form and the DNS wire name is
limited to 255 octets.


My apologies for nit-picking, but RFC 3986, Section 3.2.2 is
quite clear than DNS names in URIs are permitted to have a final
period and encouraged to do so under some circumstances.

      "The rightmost domain label of a fully qualified domain
      name in DNS may be followed by a single "." and should
      be if it is necessary to distinguish between the
      complete domain name and some local domain."

I don't think that changes the 253 octet limit, but the comment
about URIs is misleading and could contribute to an, IMO,
already high level of confusion about what RFC 3986 does or does
not specify.

The same subsection of RFC 3986 also uses the term "host
subcomponent" for what you are referring to as a name and allows
it to be a "registered name" (or <reg-name>) that might not be a
DNS name or reference at all -- whether it is or not is


Which really should never have been allowed.  Beyound the UI
everything should be absolute.  Relative names in URI really don't
work in practice because search lists are not constistent even
inside a single organisation.

I had my ISP hand me a relative link for their support pages.  IT
DID NOT WORK.  There support line got a call complaining about it.

Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka(_at_)isc(_dot_)org

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