DNS hardware advice (newbie)

[max_thomsen at my-deja.com]

john wrote:

> I'm setting up DNS (BIND, natch) for our sites. This is 
> enterprise-level, and we're getting about 250K hits a day peak - right 
> now, at least. This will probably double by the end of the year.

A single Celeron 333 will be plenty, most likely. 250k hits per day
really isn't that much. 

As I understand it, BIND likes to suck up memory, but memory usage
is dependent on the number of zones you have and the number of nodes
you advertise. 

I don't know if there's an algorithm for the number of zones X nodes
advertised = memory needed. But the key idea is this: Memory is more
critical than CPU speed. 

We (the happy company I work for and me) run BIND on FreeBSD 3.3 (or
3.4?) for 20 zones with 128 MB of RAM on Pentium 450s. We're
multi-homed to C&W and AT&T. I can't speak highly enough for BIND on
FreeBSD. FreeBSD and BIND are champs.

I doubt if any of our zones have more than 100 advertised nodes
(externally). 

The PCs we use are vast, vast, vast overkill --- though we have
nothing like the number of hits you'll have. But don't worry about
the hit rate; worry about keeping everything out of swap (paging)
space.

> My question: how much horsepower is enough (in terms of CPU and RAM, and 
> whatever else matters here)? What's a reasonable plan for hardware? I'm 
> also running Apache - I'd like to utilize the machines as fully as 
> possible, so if I could do both Apache and DNS on the same machine(s), 
> even if only for backup purposes, that'd be nice.

I wouldn't combine Apache and DNS, myself, for the simple reason
that PCs are such a cheap commodity. I'd run DNS on a cheap, cheap,
cheap box (with sufficient memory) and run Apache on a higher
horsepower box.