Subject: [Bundled-domain-names] A suggestion for 2017

From: Stephane Bortzmeyer <[email-masked]>
Date: Wed, 28 Dec 2016 19:50:30 +0000

There have been many attempts to do something with the
bundle/alias/variant issue, often with proposals to improve/remplace
CNAME/DNAME/xNAME.

One thing is missing: a repository of previous attempts, with
explanations of the problems they raise. Case in point:
draft-sury-dnsext-cname-at-apex was published six years ago, saw
almost no discussion and expired. Why?

So, IMHO, if someone wants to tackle this issue, a good start would be
to work on previous attempts.

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From: "John Levine" <[email-masked]>
Date: 28 Dec 2016 21:17:01 -0000

In article <[email-masked]> you write:
>explanations of the problems they raise.

That should be helpful, since people do seem to keep reinventing the
same well known bad ideas (WKBI's).  The conclusion we came to at the
most recent meeting is that almost all, and perhaps completely all, of
the problems with provisioning variants can be solved with better DNS
provisioning software, rather than looking for a magic DNS bullet that
will solve the problem for us.

> Case in point:

This is an excellent case in point.  It attempts to solve the problem
that you can't put a CNAME at the zone apex, by proposing an
incompatible change to CNAME that lets it work at a zone apex.  An
obvious failing is that there is no way to tell whether or not a
server or cache supports new CNAMEs, so there's no way to deploy it.

More importantly, we've already solved this problem by improving our
provisioning software.  Lots of DNS systems let you say this in a zone
file or equivalent:

foo.example. ANAME bar.example.

That tells the provisioning software to create A records for
foo.example with the contents of the A records at bar.example.
It polls now and then to see if bar.example has changed.

On my system, I have a somewhat overimplemented scheme where
I can say things like this:

  IN A [RMTIP:bar.example]

That means to replace the [RMTIP...] with records for with
the contents of records at bar.example.  If there's more
than one record it repeats the record, and as a special case, if
there are AAAA records it creates AAAA records as well.

www  IN  A   [RMTIP:www.example.org:ns1.somehost.com:A]

That says to replace the [RMTIP...] with the A record(s) for
www.example.org fetched from the name server at ns1.somehost.com.
This solves an annoying problem when I have a web site hosted
somewhere, the mail somewhere else, but the web host insists I use
their nameservers, even though there's no way to put the required MX
records on their nameservers.  Well, OK.

This sort of provisioning stuff is not hard.  I added the RMTIP stuff
to my system in an afternoon.

R's,
John

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From: tjw ietf <[email-masked]>
Date: Fri, 30 Dec 2016 06:00:24 -0500

I would love to see a solid draft appear that discussed 'CNAME at APEX' in
an attempt to standardize what every vendor has been working on.

On Wed, Dec 28, 2016 at 4:17 PM, John Levine <[email-masked]> wrote:

> _______________________________________________
> Bundled-domain-names mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/bundled-domain-names
>

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From: "John R Levine" <[email-masked]>
Date: 30 Dec 2016 13:48:20 -0500

> an attempt to standardize what every vendor has been working on.

It would be nice, but it's a big can o' worms.  The issue is that the DNS 
has two separate and only loosely connected parts.  The larger part is the 
binary query/response protocol which everyone implements, since any DNS 
client in principle has to be able to query any DNS server and understand 
the response.

The other part is the master file format and AXFR and IXFR or whatever you 
use to provide zone files or zone-file-like-things to your authoritative 
servers.  You can use whatever you want since only your own authoritative 
servers need to understand each other.  So while a lot of servers use the 
1034/1035 master file format and AXFR/IXFR, a lot don't.  They may use 
some other format (djbdns) or they may use a database (powerdns) or they 
may invent them on the fly (various hacks at Cloudflare and other places.) 
They may use rsync or database replication or something else to keep the 
servers in sync.

So while there are a lot of places with an ANAME hack (which is useful 
more places than pseudo-cname at the apex), the way they do it depends on 
a lot of stuff beyond what you can put in a master file.

Regards,
John Levine, [email-masked], Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly