Subject: [DNSOP] comment to ns-communication-00

From: [email-masked]
Date: Mon, 23 Jul 2007 23:34:46 +0900 (JST)

from ietf68 minutes,
> draft-regnauld-ns-communication-00.txt  
> Volunteers for compiling a list of services to be addressed:
>      - Kazunori Fujiwara

I could not do this work yet.

I have a comment for the draft.
Section 3.2 mentions thousands of zones synchronization.
But there is a company which operates already over 50,000 zones in one
system.

The number of zones may be over 1 million on large scale DNS providers
or registrars.

Large number of zones case, DNS protocol may not work for
synchronization because there are many refresh check
queries/timers. If there are 1 million zones whose REFRESH is 3600, At
least 1000000/3600 = 277qps REFRESH queries are generated. It is not
realistic.

To resolve this problem, another zone synchronization mechanism is
required.

But I'm afraid it may be outside of DNS protocol.
It may be implemented by database replication.

--
Kazunori Fujiwara, JPRS

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From: Harald Tveit Alvestrand <[email-masked]>
Date: Mon, 23 Jul 2007 11:24:02 -0500

> To resolve this problem, another zone synchronization mechanism is

I'm sorry, but I do not understand....

in what context is 277 operations per second a large number?
AFAIK, a REFRESH operations (for no zone change) is a lightweight operation.

                 Harald

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From: Harald Tveit Alvestrand <[email-masked]>
Date: Mon, 23 Jul 2007 11:24:02 -0500

Harald

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From: Dean Anderson <[email-masked]>
Date: Mon, 23 Jul 2007 14:10:10 -0400 (EDT)

> AFAIK, a REFRESH operations (for no zone change) is a lightweight operation.

Its a fairly high number of transactions per second for DNS servers
backed by databases.  Especially when you suppose that is just the zone
checking, and not actual queries for the "real content" records.  The
content queries (that is, the A records, etc guts in the zones that
people want) would raise the TPS by orders of magnitude.  The zone
checking would still be a (relatively) small number compared to
everything else.

However, a million authority zones on a single server is probably also
unrealisticly high.  No one has that many zones on one server. I'm
somewhat dubious of the claim that there are 50,000 zones on a single
server.  50,000 zones in one hosting provider doesn't surpise me. Of
course, if they use something like powerDNS with database backing, all
zones _can_ appear on every server.  But it would seem a poor idea to do
that, at some point.

Database backed systems have the advantage that they don't need to do
zone transfers, but can use database replication behind the scenes.

I've even seen people put cache data in databases. I found this while
searching for anycast recursive servers. [yes, that also means that
anycast clones can be detected, meaning stateful anycast isn't stable,
since if TCP "detects" two servers with the same IP address, the
connection fails.]

Anyone who did have a million zones, I think, wouldn't have it on a
single server. Or, if they did, would have some better way to improve
their transaction rates.  I can think of a few ways, but none that
require protocol changes.  I'll have to look into this draft more 
closely.

		--Dean

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From: Dean Anderson <[email-masked]>
Date: Mon, 23 Jul 2007 14:10:10 -0400 (EDT)

--Dean