regarding DNS queries for MX records...

[Jack De Winter <[e-mail]>]

I've got a fun one for everyone.  Talking with our
tech support people and doing some research, it
appears there is a DNS server out there that is sending
a DNS response back, with valid information, but it
has a response code of 6.  Now 6 is invalid as it is in
the reserved range and I can find no RFC (or draft for
that matter) that uses the return code.  The closest
I came was with the large address packets using it to
possibly say that it could accept up to a 32K DNS
query/response, but that was it.

Enclosed below is a hex dump of the query and the response
that I received.  The primary line of interest is in the
response:

97/01/02 14:47:50 MX-> ........ 0000: 00 01 85 86 00 01 00 01 

This says that the response should have a return code of 6.

So, I guess there are two main questions:

1) when doing an MX request/response, anyone have any idea
what the return code of 6 could mean?  could you point me
at a spec or draft?
2) the rest of the data in the message seems perfectly
valid.  NsLookup will accept the data as being correct.
Should I take any of the reserved return codes in the DNS
return code field and accept it as positive?  Or should I
just loudly complain?

The end effect is that it looks like our SMTP server cannot
function properly.  Any assistance or finger pointing would
be greatly appreciated.

regards,
Jack

97/01/02 14:47:49 Title: outgoing-end->0036(54) (37)
97/01/02 14:47:49 MX-> ........ 0000: 00 01 01 00 00 01 00 00 
97/01/02 14:47:49 MX-> .....mai 0008: 00 00 00 00 04 6d 61 69 
97/01/02 14:47:49 MX-> l.wildbe 0010: 6c 08 77 69 6c 64 62 65 
97/01/02 14:47:49 MX-> ar.on.ca 0018: 61 72 02 6f 6e 02 63 61 
97/01/02 14:47:49 MX-> .....    0020: 00 00 0f 00 01 
97/01/02 14:47:49 Attempt to connect to <offending server> pending
97/01/02 14:47:49 OUTG-0001: Requesting destination for mail.wildbear.on.ca
from <offending server>
97/01/02 14:47:50 Title: Input
97/01/02 14:47:50 MX-> ........ 0000: 00 01 85 86 00 01 00 01 
97/01/02 14:47:50 MX-> .....mai 0008: 00 03 00 02 04 6d 61 69 
97/01/02 14:47:50 MX-> l.wildbe 0010: 6c 08 77 69 6c 64 62 65 
97/01/02 14:47:50 MX-> ar.on.ca 0018: 61 72 02 6f 6e 02 63 61 
97/01/02 14:47:50 MX-> ......ma 0020: 00 00 0f 00 01 04 6d 61 
97/01/02 14:47:50 MX-> il.wildb 0028: 69 6c 08 77 69 6c 64 62 
97/01/02 14:47:50 MX-> ear.on.c 0030: 65 61 72 02 6f 6e 02 63 
97/01/02 14:47:50 MX-> a....... 0038: 61 00 00 05 00 01 00 00 
97/01/02 14:47:50 MX-> .,...lac 0040: 01 2c 00 0a 07 6c 61 63 
97/01/02 14:47:50 MX-> roix.*.. 0048: 72 6f 69 78 c0 2a 01 c0 
97/01/02 14:47:50 MX-> *....... 0050: 2a 00 02 00 01 00 00 a8 
97/01/02 14:47:50 MX-> ....ligh 0058: c0 00 10 09 6c 69 67 68 
97/01/02 14:47:50 MX-> tning.mg 0060: 74 6e 69 6e 67 03 6d 67 
97/01/02 14:47:50 MX-> l.6.*... 0068: 6c c0 36 c0 2a 00 02 00 
97/01/02 14:47:50 MX-> ........ 0070: 01 00 00 a8 c0 00 0a 07 
97/01/02 14:47:50 MX-> thunder. 0078: 74 68 75 6e 64 65 72 c0 
97/01/02 14:47:50 MX-> e.*..... 0080: 65 c0 2a 00 02 00 01 00 
97/01/02 14:47:50 MX-> ..,...ns 0088: 00 01 2c 00 05 02 6e 73 
97/01/02 14:47:50 MX-> .*.[.... 0090: c0 2a c0 5b 00 01 00 01 
97/01/02 14:47:50 MX-> ..Q..... 0098: 00 01 51 80 00 04 c7 f6 
97/01/02 14:47:50 MX-> ...w.... 00a0: 84 02 c0 77 00 01 00 01 
97/01/02 14:47:50 MX-> ..J[.... 00a8: 00 01 4a 5b 00 04 c7 f6 
97/01/02 14:47:50 MX-> ..       00b0: 84 03 
97/01/02 14:47:50 MX-> Packet size = 178, ans = 1, auth = 3, add = 2

-------------------------------------------------
Jack De Winter - Wildbear Consulting, Inc.
[phone]		http://www.wildbear.on.ca/

Author of SLMail(95/NT) (http://www.seattlelab.com/) and other great products.