Reverse for a /23

[Mark.Andrews at iengines.com]

> You could use the $GENERATE directive to ease a lot of the work in this
> situation. Something like:
> 
> $GENERATE 1-254 $ PTR somehost$.example.com.
> 
> You still have 128 files to create, but only one entry per file instead of
> 254.

	$GENERATE is much more useful in the parent zone.

	For a lower /25

	0-127	NS	ns1.example.
	0-127	NS	ns2.example.
	$GENERATE 0-127 $ CNAME $.0-127

> 
> I've only used the $GENERATE directive a little bit, so you may have to play
> with it a bit to get it to do exactly what you want.
> 
> The only thing you might need to be careful of is leaving out the class (the
> place where you normally put "IN"), since $GENERATE puts it in for you. That
> one drove me crazy trying to figure out what I had done wrong the first time
> I used it.

	The class is not needed as a master file only contain one class.

> 
> On that note, because of how $GENERATE works, can you not use it on other
> classes (like CH or HS)? I know other classes are rare these days, but it
> should be a class agnostic directive, shouldn't it? If for no other reason
> than symmetry with the regular entries.

	$GENERATE is class independant.
	It works for all classes.
> 
> Just a thought,
> 	Adam Augustine
> 
> -----Original Message-----
> From: gah at ugcs.caltech.edu [mailto:gah at ugcs.caltech.edu]
> Sent: Wednesday, December 22, 1999 4:37 PM
> To: comp-protocols-dns-bind at uunet.uu.net
> Subject: Re: Reverse for a /23
> 
> 
> Stephen Amadei <amadei at dandy.net> writes:
> 
> (snip about RFC2317)
> 
> >O.K... I had heard RFC2317 was for doing reverse breaking _any_ of the
> >octets... not just the last one.
> 
> >Then what would be done, for say a /17 reverse?  Create 32768 reverse
> >files?
> 
> No, 128 files with 256 entries each.
> 
> For a /9 you would need 32768 files, though with that many hosts
> you might delegate some of them.
> 
> Actually, the RFC2317 method was not originally for subnetting, it was
> when I had a few addresses on the campus backbone and wanted to be able
> to do the reverse for them.  It works for any case of delegating less
> than an entire /24, as was said, down to /32 (one host).
> 
> -- glen
> 
--
Mark Andrews, Internet Engines Inc. / Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at iengines.com