RE: Operational experience with 3 degrees

["Jeroen Massar" <jeroen@unfix.org>]

JINMEI Tatuya wrote:

<SNIP>

> BTW: we may need to raise this issue in a place where DNS experts are.
> Perhaps dnsop?

That might be quite a good place indeed as it is mostly DNS orientated.
Subject change would be nice too :)

> >> - some ignore AAAA queries (causing a delay to fallback).
> >> you can see this when you try to resolve AAAA for "ftp.mozilla.org"
> >> at 64.12.182.70 (gdns-02-ftp-dom.ns.aol.com)
> 
> > And those boxes do not ignore A queries for the same name?
> 
> No.  The boxes only ignore AAAA (actually non-A) queries, but process
> A queries correctly.
> 
> > The reason I'm asking is because I think there are DNS servers which
> > silently ignore queries for names that they don't have any 
> information
> > (instead of sending a referral).
> > If they treat A and AAAA differently that would be news to me.
> 
> The following is a more detailed description.  
> 
> If you try to resolve an RR for ftp.mozilla.org, you'll follow a CNAME
> chain and will eventually see the name is in fact an alias for
> ftp-mozilla.gftp-mozilla.netscape.com.

<SNIP>

From RFC2181:
8<-----------------------------
10.1. CNAME resource records

   The DNS CNAME ("canonical name") record exists to provide the
   canonical name associated with an alias name.  There may be only one
   such canonical name for any one alias. 
----------------------------->8

I interpret this as "CNAME chains are not allowed" thus the above
system should not work at all... apparently in some cases it works
though.
I wonder why this does work for A records ;)

Greets,
 Jeroen