DNS Server Farm

[Javi Lavandeira]

Hi,

> Our company has inherited/bought an ISP outfit which has around 2 
> million subscribers. Among our first priority is to upgrade the DNS 
> service which has been abysmal according to the users
> 
> Can someone give me a head-start on a recommended configuration for such 
> DNS outlay which serves 2M+ dial-up users?

I assume the DNS server(s) will be doing name resolution and caching for
your customers , am I right? Will you also be hosting the DNS zones of
your customers' domains? How many maximum concurrent users do you have?

I would go for a djbdns box (http://cr.yp.to/djbdns.html). Use tinydns
to serve your DNS zones, and dnscache to provide resolving anc caching. Probably
you won't be needing a very powerful machine, but since your company
seems to have enough resources, I guess it won't hurt to buy a big one.

About the performance, two quotes from the djbdns FAQ:

"One site reported receiving 500 queries per second per server at peak
times for data from a 350-megabyte data.cdb. The tinydns process handled
about 7000 queries per second of CPU time. The CPU was a Pentium III-550.
This example, and lab tests, suggest that tinydns can easily handle the
.com server load. However, I don't have enough data on the distribution
of .com queries to carry out a realistic experiment."

"cr.yp.to, which among other things handles a million mailing-list
deliveries in a typical week, has been using dnscache since Christmas
1999. In a typical 4-week period, dnscache used 128 minutes of CPU time
on a Pentium II-350, handling 13.7 million queries and receiving 210
megabytes of data to cache.
I did a huge Internet survey through dnscache, handling nearly a million
PTR queries for random IP addresses in 4.5 hours on a Pentium-133."

So, I would advice to install djbdns and do some stress tests. Then you
can decide whether you'll be needing another machine or not.

Best regards,

--
Javi Lavandeira <javi at isr.co.jp>
International Systems Research
http://www.isr.co.jp