[122447] in North American Network Operators' Group
Re: Time out for a terminology check--"resolver" vs "server".
daemon@ATHENA.MIT.EDU (Larry Sheldon)
Sun Feb 14 20:13:24 2010
Date: Sun, 14 Feb 2010 19:12:43 -0600
From: Larry Sheldon <LarrySheldon@cox.net>
CC: nanog@nanog.org
In-Reply-To: <20100215001013.08A4E2282E@thrintun.hactrn.net>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 2/14/2010 6:10 PM, Rob Austein wrote:
> At Sun, 14 Feb 2010 18:02:48 -0600, Laurence F Sheldon, Jr wrote:
>>
>> I thought I understood but from recent contexts here it is clear that I
>> do not.
>>
>> I thought a resolver was code in your local machine that provide
>> hostname (FQDN?), given address; or address, given host name (with
>> assists to build FQDN).
>>
>> And I thought a "server" was a separate program, might be on the same
>> machine, might be on another machine (might be on the local net, might
>> be distant) that the resolver code called for information that was not
>> in local cache.
>>
>> Just what is the straight scoop?
>
> No doubt Olafur will beat me up yet again for not having written the
> DNS lexicon years ago, but:
>
> - A "resolver" is something that implements the "resolver" (ie,
> client) role in the DNS protocol. It might be a stub resolver, the
> client side of a recursive nameserver, a pure iterative resolver,
> ....
>
> The defining characteristic is that it send queries (QR=0) and
> receives responses (QR=1).
>
> - A "name sever" is something that implements the "nameserver" (ie,
> server) role in the DNS protocol. It might be an authoritative
> nameserver, the server side of a recursive nameserver, ....
>
> The defining characteristic is that it receives queries (QR=0) and
> sends responses (QR=1).
>
> Clear enough?
Yes--tracks with what I thought, pretty much--I was missing the
clientness of the resolver code to go with the serverness of the server.
> Mapping protocol definitions onto the plethora of terms used by
> operators in the field is left as an exercise for the reader, no
> sarcasm intended. DNS is an old protocol, there are an awful lot of
> people who think they understand it,
I am one of those is sure he understands it--which belief crumbles when
I try to explain it to somebody else.
and each of those people has
> their own set of terms that they're comfortable using. The
> definitions above are what I rammed through the IETF during several
> rounds of standards writing, but I would be the first to admit that
> not everybody uses the terms the same way as I do.
DNS arcana is one of the things that somebody should document on the
internet-history list while there are still people around who can do so
with some authority.
Thanks.
--
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