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Re: [dnsext] RFC 6604 Clarification

"W.C.A. Wijngaards" <wouter@nlnetlabs.nl> Tue, 31 March 2015 07:22 UTC

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Date: Tue, 31 Mar 2015 09:22:19 +0200
From: "W.C.A. Wijngaards" <wouter@nlnetlabs.nl>
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Subject: Re: [dnsext] RFC 6604 Clarification
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Hi Kumar,

I cannot answer on the RFC part, but I want to answer on what will
make the resolver continue the lookup.

On 30/03/15 11:04, Kumar Ashutosh wrote:
> Hi
> 
> As per RFC 6604, section 3
> 
> When an xNAME chain is followed, all but the last query cycle
> 
> necessarily had no error.  The RCODE in the ultimate DNS response
> 
> MUST BE set based on the final query cycle leading to that
> 
> response.  If the xNAME chain was terminated by an error, it will
> 
> be that error code.  If the xNAME chain terminated without error,
> 
> it will be zero.
> 
> 
> 
> This is a little vague on two accounts:
> 
> 1.What would be the error code if the server decides to curtail
> the CNAME chain after a certain length (say 20). Is it still
> success or do we indicate in some other way.

The curtailed CNAME chain is best sent with RCODE NOERROR(0).

> 
> 2.If the CNAME chain points to a Qname for which the auth server
> is non-authoritative (and recursion is disabled on the auth
> server.) The server in this case cannot get the response. A direct
> query for this Qname will result in SERV_FAIL. Should the auth
> server return SERV_FAIL in this case? Will resolvers respect
> answers with SERV_FAIL in RCODE and cache the partial response?

You must send the partial response with RCODE NOERROR(0).  Then, the
resolver can retry after the CNAME.

Best regards,
   Wouter


> 
> 
> 
> Can we put a clarification?
> 
> 
> 
> Thanks
> 
> *Ashu*
> 
> Program Manager | Windows Networking| DNS
> 
> 
> 
> 
> 
> _______________________________________________ dnsext mailing
> list dnsext@ietf.org https://www.ietf.org/mailman/listinfo/dnsext
> 

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