Hardware

[stuart nichols]

On 15 Aug 1999, Benjamin John wrote:

> Is a 486 DX/2 66 with 16 Megs of ram enough for a DNS server ? DNS is
> the only thing being done on this machine and it is serving 3 domains.

The State of Texas has scores of nameservers that are on 486 boxes.
Virtually all of them are running FreeBSD.  The main DNS for my
agency is a 486 DX2/66 with 64MB ram, but we have some that have
much less memory.  Here are the bootup details from a nameserver 
for a small, outlying network, serving four (small) primary zones 
and two secondaries:

  Aug  4 04:45:41 shemp /kernel: FreeBSD STAC-ALT-RELEASE #0: 
                                 Wed Sep 18:23:27:12 CDT 1998
  Aug  4 04:45:41 shemp /kernel:
  Aug  4 04:45:41 shemp /kernel: CPU: i486DX (486-class CPU)
  Aug  4 04:45:42 shemp /kernel: real memory  = 8650752 (8448K bytes)
  Aug  4 04:45:42 shemp /kernel: avail memory = 6840320 (6680K bytes)
  Aug  4 04:45:42 shemp /kernel: Probing for devices on the ISA bus:
  Aug  4 04:45:42 shemp /kernel: sc0 at 0x60-0x6f irq 1 on motherboard
  Aug  4 04:45:42 shemp /kernel: sc0: VGA color <16 virtual consoles,
                                 flags=0x0>
  Aug  4 04:45:42 shemp /kernel: ed0 at 0x280-0x29f irq 5 maddr 0xd8000
                                 msize 8192 on isa
  Aug  4 04:45:42 shemp /kernel: ed0: address 00:80:48:81:66:0d, type
                                 WD8003E (8 bit) 


Yes, that's 8MB ram, and an old WD8003 ethernet card.  This machine
does recursive lookups for the other machines in the that office,
as well as hosting a small website and acting as the SMTP and popmail
server.  Market value of this machine--about $40.    As you can see 
below, it is not overly busy (on a Sunday afternoon, at least):

  soho27: {2} uptime
   4:35PM  up 11 days, 11:50, 2 users, load averages: 0.12, 0.06, 0.01



So it's quite possible to have a 486 or a low-level pentium as
a nameserver.  I wouldn't try running a WinNT nameserver on a
486 with 16MB, but with FreeBSD it'll work just fine, depending
on how big the zones are and how many users are getting their
recursive lookups through it.  DNS responses are small and fast,
so the limit that you need to worry about is how big the cache
will grow, not the CPU speed.  That 8MB machine mentioned above
is on a LAN that is connected to the rest of our net by ISDN,
and can easily keep up with any amount of traffic that could
come and go over an ISDN line at 128K.  We would have to upgrade
the ISDN line before we would have to upgrade that nameserver.

Memory is cheap, by the way, so if you have 72-pin simm slots
in that box it would only cost you a few bucks to add another
simm or to replace one with a larger one.  On a 486 motherboard 
the 72-pin simms can be added one at a time and don't have to
match each other in size.

stu

The State Technology Assessment Center of Texas