non-24 bit subnets

Jay Ford jay-ford at uiowa.edu
Wed Oct 6 20:27:50 UTC 2010


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.

________________________________________________________________________
Jay Ford, Network Engineering Group, Information Technology Services
University of Iowa, Iowa City, IA 52242
email: jay-ford at uiowa.edu, phone: 319-335-5555, fax: 319-335-2951



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