Upper limit to # of zones in a BIND config file

[Mark_Andrews at isc.org]

> 
> I have a situation where I would like to run BIND 8.2.1 with
> a configuration file containing at least one million zone
> directives. I saw something on the ISC web site that made
> me hopefull that this could be done. Namely, at
> 
>  http://www.isc.org/view.cgi?/products/BIND/plans.phtml
> 
> it lists BIND version 8.2 enhancements to include "Extensions
> to permit over 16 million zones per server".
> 
> But in my dual CPU Ultra 60 (w/ 2 GB of RAM) environment I am
> seeing results that indicate to me that even one million zones
> is impractical if not impossible for BIND to manage. It simply
> is taking far too long for BIND to load such a large config
> file apparently. Right now I've been waiting on a reload of
> the config file that has been going on for over a half hour,
> and the log file indicates that I have yet to reach even the
> 500000 zone mark.

	Well the zone array is built up 64 zones at a time.  With
	the zone arrays contents copied onto the new array each
	time.  This and the other work required to set up a zone
	takes time, however you can eliminate the coping of the
	zones by setting NEWZONES appropriately when you build.  

	I'm aware of real life configurations ~100k zones.

	1 M zones will take ~324Mb just for the zone structures them
	selves let alone any other memory attached to them.
> 
> Here is how I am defining the zones in named.conf:
> --------------------------------------------------------------
> zone "."                    { type hint;   file "named.root"; };
> zone "0.0.127.in-addr.arpa" { type master; file "named.127"; };
> 
> zone "test1.com"               {type master; file "dns.dev";};
> zone "test2.com"               {type master; file "dns.dev";};
> 		...
>   [test3.com through test999999.com appear here]
> 		...
> zone "test1000000.com"               {type master; file "dns.dev";};
> --------------------------------------------------------------
> Can anyone tell me what the "16 million zones" is referring to?

	The range of the index variable into the zone array,
	0 .. (2^24-1).

	Mark

> If this is just a theoretical limit (based on a buffer size lying
> about somewhere in the source code perhaps?), does anyone know
> what the practical limits to BIND 8.2.1 might be in this area?
> 
> Walter Chick
> Boston Light Software
> 
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org