Reverse for a /23

[Adam Augustine]

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.

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.

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.

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