[dns-operations] Signaling client protocol to authority

Edward Lewis Ed.Lewis at neustar.biz
Sun Jan 16 16:08:36 UTC 2011

At 8:09 -0500 1/16/11, Patrick W. Gilmore wrote:

>We already have a suggestion to signal the client IP address, signaling the
>protocol the client used seems even easier.  So it shouldn't be too
>difficult. Right?

In a query, one can divide the bits of information into two 
categories - the data questions (QNAME, etc.) and control data. 
Currently the control data is hop-by-hop, as opposed to the data 
question is end-to-end (with the ends being the application and the 
zone authority).  I can't think of any control data that currently is 
specified to go end-to-end.

I.e., when the RD bit is turned on from the stub to the recursive 
server, the recursive server will turn the RD bit off while it works. 
The CD bit will be on from a client that plans to do it's own 
validation, even if the CD bit was off in the prompting request.

And I say "currently" because there is a IETF draft on source IP 
option in the works.  The draft exists but has not achieved any 
consensus.  As much as I lean in favor of the option being specified, 
I think it is pretty clear that it is not accepted by all and even if 
it gets to that point, whether it would be successful (in that it 
hasn't been put to production).  Note: the latter expression of doubt 
is not based on the proposal, but its immaturity.

So - I'd say it (what network protocol was used) would be difficult 
in the sense that such an option would be precedent setting in 

>I'll sit back and wait for people to explain how confused I am now. :)  Thanx
>for your time.

As for the utility of the access information, I have my doubts.  The 
reason is that in DNS, if you want the v4 you ask for "A" and if you 
want v6 you ask for "AAAA".  At my house, for some time now, I have 
native v6 from my provider.  The DNS serves in /etc/resolv.conf are 
still all v4 but when I access www.apnic.net I use v6 for http.  (I 
have a collection of Macs, not all choose v6 over v4, I haven't had 
the time nor enough interest to see if there is some rhyme or reason.)

I realize that any computer might load up an application that is 
trying to be enlightened and ask for v6 and v4, and while the 
computer might have a v6 prefix it has no routing.  It's tempting to 
think that if I had to do DNS over v4, I can only do HTTP over v4 but 
my own house is a counter-example.

Edward Lewis
NeuStar                    You can leave a voice message at +1-571-434-5468

Jan 11, 2011 - Either it's 1/11/11 or 11/1/11,  "Junior Saint Broadcast day"
(Nov 11 is senior...)

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