[cifs-protocol] [REG: 111092947767946] Question about MS DNS behavior regarding DNS packets containing multiple questions

Edgar Olougouna edgaro at microsoft.com
Thu Oct 6 16:38:08 MDT 2011


Kai,

We confirm that Microsoft DNS implementation only supports one question per question section in a query. As a result, Windows-based DNS servers return DNS_ERROR_RCODE_FORMAT_ERROR when the request contains more than one question.

Per the RFC1035, it looks permissible to ask multiple questions in a query packet. However, the longstanding de-facto standard in DNS is to support a single question per packet. For instance, BIND servers are also thought to support one question per packet.

As it turns out, current Microsoft's DNS implementations do not have extensions to DNS RFC standards. We are reviewing the best option to publish an informative content to prescribe that clients should not attempt to ask multiple questions in the same DNS packet. This would eventually be in the form of a KB article.

Regards,
Edgar

-----Original Message-----
From: Edgar Olougouna 
Sent: Thursday, September 29, 2011 11:31 AM
To: Kai Blin
Cc: pfif at tridgell.net; cifs-protocol at samba.org
Subject: [REG: 111092947767946] Question about MS DNS behavior regarding DNS packets containing multiple questions

[Adding case number in subject]

Kai,

I will investigate this and follow up.

Regards,
Edgar

-----Original Message-----
From: Tom Jebo 
Sent: Thursday, September 29, 2011 8:24 AM
To: Kai Blin
Cc: Interoperability Documentation Help; pfif at tridgell.net; cifs-protocol at samba.org
Subject: RE: Question about MS DNS behavior regarding DNS packets containing multiple questions

Hi Kai,

Thanks for this question about FORMERROR and Microsoft DNS server not following RFC 1035.   One of the Open Specifications team will contact you shortly to assist. 

Best regards,
Tom Jebo
Escalation Engineer
Microsoft Open Specifications


-----Original Message-----
From: Kai Blin [mailto:kai at samba.org] 
Sent: Thursday, September 29, 2011 1:05 AM
To: Interoperability Documentation Help; pfif at tridgell.net; cifs-protocol at samba.org
Subject: Question about MS DNS behavior regarding DNS packets containing multiple questions

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Hi folks,

I've stumbled over the MS DNS server not quite following the behavior described in RFC 1035 with regards to the number of questions it will allow in the question section.

RFC 1035 states:

4.1.2. Question section format

The question section is used to carry the "question" in most queries, i.e., the parameters that define what is being asked.  The section contains QDCOUNT (usually 1) entries, each of the following format [...]


However, the Microsoft DNS server seems to give back a FORMERROR error code if I specify more than one question. Can I get clarification on where this behavior is documented?

Cheers,
Kai

- --
Kai Blin
Worldforge developer http://www.worldforge.org/ Wine developer http://wiki.winehq.org/KaiBlin Samba team member http://www.samba.org/samba/team/ -----BEGIN PGP SIGNATURE-----
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