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Subject: Re: [OT] DNScache
From: Bennett Todd (betrahul.net)
Date: Mon Apr 17 2000 - 13:29:53 CDT

2000-04-17-10:02:16 Wietse Venema:
> Can dnscache/tinydns handle a root name server?

A root nameserver, effortlessly. The data.cdb constant database,
which needs a total of 3 lookups (the first is always the first
block, so it'll always hit cache after the first record), isn't
badly bulky; for a root nameserver (serving only the TLDs) the
data.cdb is well under 200KB. Any reasonable system would keep the
database entirely in cache.

Now for a main nameserver, after the style of the
?.root-servers.net, serving root as well as all of .com, .edu,
.org, and .net, the answer is no, not with the current version of
dnscache; tinydns-data maxes out at c. 70,000 domains, at which
point it hits the 2GB limit of cdb, and so would be a PITA to keep
in cache:-).

If there were interest in running such a nameserver, it wouldn't be
that hard; it'd just require a different record format, oriented
more towards space efficiency and somewhat less towards code
simplicity.

Tinydns is an exercise in using the absolute minimum of code needed
in the daemon. The tinydns-data program essentially composes the
answers to every query that tinydns will honor, and the data.cdb
file is a key->value mapping of query to reply. A nameserver for
millions of domains would justify a data structure that would apply
more code in the daemon to delivering answers from a more compact
data format.

-Bennett

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