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Re: [apps-discuss] Last Call: <draft-ietf-appsawg-nullmx-05.txt> (A NULL MX Resource Record for Domains that Accept No Mail) to Proposed Standard

2014-07-17 17:49:48


--On Thursday, July 17, 2014 14:38 -0700 "Murray S. Kucherawy"
<superuser(_at_)gmail(_dot_)com> wrote:

Specifically referring to Section 3 of
draft-ietf-appsawg-nullmx-05, there is not such thing as a
"NULL MX Resource Record".  There is only an MX Resource
Record that this specification proposes to use with a
convention involving specific content in the DATA.  One
could call that many things, but "NULL MX Resource Record"
isn't one of them.

By my reading of that section, it is defining the term, if
only by virtue of the way it is used in the name of that
section.

Perhaps your confusion would be resolved if the term had a
comma in it, so:  NULL, MX Record?

In other words, NULL is an adjective within the term.

I don't want to get into grammatical hair-splitting if that can
be avoided, but the current construction names an RR type that
doesn't exist and punctuation doesn't help.  As I said, if we
didn't already have a use problem with DNS terminology, it would
be a non-issue.
 
If you would prefer a different term, please suggest one.

That particular problem would be easily solved by saying 

    "MX Resource Record with a null value"

or even 

    "MX Resource Record that, by convention, points at the root"

The latter is a little long for a section title, but it exactly
reflects what is going on.   I would still like a consensus
opinion from DNSOP both generally and for the specific reason
that a reasonable person might assume that a resource record
with a null value would have an empty DATA field, not one with a
value, even a value pointing informally at the root, so the
question of whether the DNS Experts find "null value"
problematic is actually important.   I can't remember whether
resource records with a zero-length DATA field are even allowed,
but we should know for certain before throwing terms like "null
value" around.  And, whether this document can, procedurally,
define "null value" as meaning something different from what it
might mean elsewhere in the DNS (were that the case) that would
be, IMO, a Really Bad Idea.

I mentioned this to one of the co-authors privately, but since
you just reminded me of it, I'll mention it here too:

The use of NULL (i.e., in all-caps) makes me think of it more
as either an acronym or a mnemonic.  For example, in C, the
special pointer with address zero is written in prose as "the
null pointer", but in source code simply as "NULL".  Since
this draft is more prose than code, my sensibilities would
prefer it be written as "null" in this document rather than
"NULL". In its current form, I might expect to find a special
RR type definition for NULL MX and/or corresponding
definitions in the appropriate C header files.

Yes, exactly.  That isn't, IMO, the problem, but it certainly
makes it worse (more confusing).  See above.

This is not a major point since I'm the only one to mention it
so far, but there you have it.

Consider it as getting an extra mention.  Ultimately, the text
should be clear whether caps are used or not, but the use of the
caps in these contexts doesn't make things any easier.

   john