Re: Operational experience with 3 degrees

[JINMEI Tatuya / $B?@L@C#:H(B <jinmei@isl.rdc.toshiba.co.jp>]

>>>>> On Mon, 24 Mar 2003 11:21:24 +0100 (CET), 
>>>>> Erik Nordmark <Erik.Nordmark@sun.com> said:

>> I guess there may be a comprehensive document already, but I myself
>> don't know one.

> It seems useful to take your list (and other issues folks report)
> and put in an I-D as a starting point.

(I'll first answer the second point) okay, if no one else has a
comprehensive list, I'll try to make one.  (I'm not sure if an I-D is
the best place to describe this kind of topic, but an I-D is probably
not a bad one.)

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

>> - 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.

Also, you'll see 64.12.182.70 (gdns-02-ftp-dom.ns.aol.com) is an NS
for the gftp-mozilla.netscape.com zone.  Now we're ready to do some
experiments.

The server answers a query for an A RR:

% dig a +norec +short @64.12.182.70 ftp-mozilla.gftp-mozilla.netscape.com.
64.12.168.243

but (apparently) ignore a query for a AAAA RR:

% dig aaaa +norec +short @64.12.182.70 ftp-mozilla.gftp-mozilla.netscape.com.
;; connection timed out; no servers could be reached

or for an MX RR:

% dig mx +norec +short @64.12.182.70 ftp-mozilla.gftp-mozilla.netscape.com.
;; connection timed out; no servers could be reached

or for an A6 RR:

% dig a6 +norec +short @64.12.182.70 ftp-mozilla.gftp-mozilla.netscape.com.
;; connection timed out; no servers could be reached

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					jinmei@isl.rdc.toshiba.co.jp