non-24 bit subnets

[Alex McKenzie]

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Jay Ford wrote:
> On Wed, 6 Oct 2010, Alex McKenzie wrote:
>> Out of curiosity:  what if it's a /16 or /8 network?  Do those also get
>> built as 24 bit files, or can they be built differently?  I seem to
>> recall seeing an option for a reverse lookup file with hosts declared as:
>>
>> x.y    PTR    host.domain.tld.
>>
>> Does that work, or was that an old format that's been deprecated, or
>> would it never have worked?
> 
> Sure, that works
> 
> For the /16 case, define the zone like b.a.in-addr.arpa & define records
> like
> "d.c PTR name." for address a.b.c.d.
> 
> For the /8 case, define the zone like a.in-addr.arpa & define records like
> "d.c.b PTR name." for address a.b.c.d.
> 
> Note the order of the address components in the zone file, with least
> significant furthest left.

Got it.  So basically bind can cope with a subnet that falls on an octet
boundary, but not inside an octet.  That's unfortunate for my purposes,
but not unreasonable.

Since we actually control the full /16 network (it's an internal NATed
network), I may just build my files to match our actual subnets, then
include them all this way.  I suspect that will wind up with the best
balance of human-readability to computer-readability.


Thanks again to everyone who responded:  I've had to learn DNS and bind
as I went along, so there are some fairly large holes in my
understanding.  (Actually, my understanding is probably 99% holes, with
a couple of threads stretching across where I've had to make something
work....)

- -Alex
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