[dns-operations] Why are cnames called "canonical" names?
Mark E. Jeftovic
markjr at easydns.com
Fri Apr 10 02:05:28 UTC 2015
Again, I'm not explaining myself clearly.
The question isn't "which side of a cname is the canonical name", the
question is "why did they decide to call it 'canonical'" (as opposed to
calling it some other word than 'canonical' that meant exactly the same
thing as what 'canonical' means.
It's just not intuitive (to me) as to why that specific actual word
(which has biblical meanings but no ostensible technical ones, read on)
In other words my question is "what is the etymology of the term
'canonical' in the sense that it's used in the DNS CNAME RR"
I hope the person who emailed me off-list does not mind that I paste a
snippet of what he told me here:
""canonicalizing" can be found mentioned as early as K&R's _C_ at least
as a concept (pre-dating the patent nonsense about number formats on the
wire). It's mentioned in the sense of promotion of numbers.
In essence the general concept (as it pertains to numbers anyway) is
that it's a lot easier to write N*2 convertors (one each way) to a
representational format powerful enough to represent all N formats than
it is to write N*(N-1) convertors to convert directly between them.
So "canonicalizing" names doesn't mean quite the same thing but the
concept is that "WWW" should work everywhere, it's a canonical name for
a service. They could have just used A RRs, but the responsibility for
maintaining the service might not be the same as that for infrastructure."
That's the sort of explanation I was after.
Mark Andrews wrote:
> In message <55272759.9030605 at easydns.com>, "Mark E. Jeftovic" writes:
>> Thanks but that page doesn't go into why the term "canonical" was
>> adopted, as opposed to "alias" (which makes sense), or even "knickname",
>> "doppelganger" or something like "pointer".
>> Somebody did send me a very comprehensive background off list which goes
>> back to Kernighan & Ritchie's "C" book.
>> - mark
> The target (RHS) of the CNAME is supposed to be the official
> (canonical) name of the entity (though nameservers are required to
> handle CNAME chains when this requirement is not being met).
> The LHS is the alias.
> The RHS is the canonical name.
> Think of CNAME as "the canonical name of this alias is ..."
> Now if were providing a list of alias for this entity then ALIAS would be
> the right name for the record and more than one of them would be supported.
>> Roland Dobbins wrote:
>>> On 10 Apr 2015, at 6:26, Mark E. Jeftovic wrote:
>>>> Is it in the "accepted as genuine" sense of "included in the list of
>>>> sacred books officially accepted as genuine" definition of "canonical"
>>>> that led to this?
>>> Roland Dobbins <rdobbins at arbor.net>
>>> dns-operations mailing list
>>> dns-operations at lists.dns-oarc.net
>>> dns-jobs mailing list
>> Mark E. Jeftovic <markjr at easydns.com>
>> Founder & CEO, easyDNS Technologies Inc.
>> +1-(416)-535-8672 ext 225
>> Read my blog: http://markable.com
>> dns-operations mailing list
>> dns-operations at lists.dns-oarc.net
>> dns-jobs mailing list
Mark E. Jeftovic <markjr at easydns.com>
Founder & CEO, easyDNS Technologies Inc.
+1-(416)-535-8672 ext 225
Read my blog: http://markable.com
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