True, strictly from a per-hop latency standpoint, there shouldn't be much
difference between forwarding a packet or forwarding a DNS query.
Having said that -- and I'm sure the BIND developers could elaborate further on
this -- I know that there's big difference between processing *packets*, from,
say, a routing standpoint, which customized ASIC-level hardware can do to the
tune of millions per second, and processing *queries*, which are much
higher-level constructs, with a lot more variation, more levels of parsing,
disassembly, re-assembly, validation, etc. When you have multi-hop DNS
forwarding, you're using up significant resources on multiple computing devices
at once, in ways that don't necessarily lend themselves to optimization in
hardware. It ends up being the opposite of parallelism, i.e. using the
resources of multiple devices to accomplish something that could, with only
configuration changes, be accomplished with the resources of only one device.
At the risk of sounding xenophobic, there seems to be a mindset among certain
cultures that forwarding is "natural", and, in contrast, having DNS instances
talk to each other directly is somehow "artificial". I've had this conversation
many times with many of my European counterparts over the years, and we just
seem to view things differently. One could speculate on the difference in world
view -- submission to higher authority, perhaps? Hierarchical social
organization? I don't know -- I don't claim any expertise whatsoever in
sociology, cognitive psychology, or related fields. But for me, and I think
most people in my (North American) culture -- possibly because we tend more
towards individualism and/or egalitarianism? -- having DNS instances talk
*directly* to each other, as "equals" or "peers", is much more natural than one
DNS instance relying upon another to handle all of its resolution needs (thus
making the first instance subservient, in a sense, to the second), which then
relies on another, and to another, and so on, in a daisy chain.
Again, maybe it's just a different mindset/world-view. Or, perhaps I'm
over-generalizing a cultural difference from a relatively-small sample of
conversations. But, as I touched on in my second paragraph, there may be some
objective reasons to eschew forwarding, particularly multi-hop forwarding.
- Kevin
-----Original Message-----
From: bind-users [mailto:bind-users-boun...@lists.isc.org] On Behalf Of
Willmann, Robert
Sent: Friday, August 12, 2016 1:33 AM
To: bind-users@lists.isc.org
Subject: RE: Delegation questions
Kevin Darcy wrote:
>
> In any case, multi-hop forwarding is always the least-preferred option.
>
I wonder for which reason do you think this.
Of course, any forwarding adds a additional hop and therefore additional delay
and an additional possible point of failure.
But this is true for any network-connection.
So, what do you think are the DNS-specific downsides of forwarding?
The only thing that comes to mind if I think about downsides of forwarding is
that, if something goes wrong, the client only gets a generic SERVFAIL as
errormessage instead of a specific explanation what exactly went wrong.
Do you see other downsides to forwarding?
Mit freundlichen Grüßen
Robert Willmann
--
Commerzbank AG
Group Information Technology
GS-IT 8.2.3 Core Services
Postanschrift: 60261 Frankfurt am Main
Geschäftsräume: Mainzer Landstr. 151, 60327 Frankfurt am Main
Tel.: +49 69 136 - 290 71
Fax: +49 69 136 - 590 71
robert.willm...@commerzbank.com
Commerzbank AG, Frankfurt am Main http://www.commerzbank.de Pflichtangaben
http://www.commerzbank.de/pflichtangaben
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