Setting up a Root name server

[Michael Milligan]

Barry Margolin wrote:
>>
>> Local copies of the top-level domains could be useful if you were running
>> applications that performed enormous numbers of DNS lookups in rapid
>> succession.  For instance, a web server log analyzer would probably be
sped
>> up noticeably if you had a local copy of the IN-ADDR.ARPA zone.  You
could
>> also perform well on DNS benchmarks.  However, I think you'd see less
>> benefit to normal user DNS lookups.
>>


Amen.

Chris wrote:
>
>Ok, how about 10,000+ users hammering the DNS?
>


How often?  If you're talking average users, that number *might* get you up
to 10 query per second if they all pointed to the same box.  That's from my
experience at a 120,000+ person company.

Have you done hit statistics on your DNS servers?  What's your cache hit
rate?  Of the misses, how many missed by only one zone cut (i.e., had to
make one query to an offsite NS)?  (finding the answers is left as a
learning excercise for you)

You'll find that after initial bootstrap, a DNS server caches who the roots
are, who the COM servers are, who the NET servers are, etc. (most TLDs
basically) and after that, it's talking to a TLD server (like COM)  if it
doesn't have a particular SLD (second-level domain) and then to SLD servers.
I think you'll then find that almost *all* of your latency is due to your
server having to talk to (and time out talking to) SLD servers and TLD
servers, with *most* of the latency coming on average from the SLD
component.

What started this thread was a desire to setup your own root to speed things
up.  Well, it just doesn't work that way, as so eloquently explained by
several folks here... unless you retrieve and serve *all* the DNS
information you want to find out about from your own local servers.  DNS
doesn't take kindly to having non-official things throw into it (it tends to
spit them out), so you have to contain it yourself.  And there's the rub --
it is completely impractical to "copy" the database in that fashion, and
even doing part of it (root zone, COM zone) is not going to make much of a
dent in your overall resolution time.

It is, ultimately, a space-time tradeoff with an important twist -- the data
is constantly changing.  If you can figure out a faster way to do DNS on the
scale it's done today, record changes and all, write an RFC and I'll stand
behind you.

Regards,
Mike

--
Michael Milligan - Acme Byte & Wire LLC - milli at acmebw.com