Time out for a terminology check--"resolver" vs "server".

Larry Sheldon LarrySheldon at cox.net
Mon Feb 15 01:12:43 UTC 2010

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.

"Government big enough to supply everything you need is big enough to
take everything you have."

Remember:  The Ark was built by amateurs, the Titanic by professionals.

Requiescas in pace o email
Ex turpi causa non oritur actio
Eppure si rinfresca

ICBM Targeting Information:  http://tinyurl.com/4sqczs

More information about the NANOG mailing list