direct master reverse CIDR zone without $GENERATE?

[Mark Andrews]

> Hi Everyone,
> 
> I was wondering if it was possible to have a master zone for a partial
> (sub-24 CIDR) reverse zone, without using $GENERATE.  The problem is
> that a master zone 3.2.1.in-addr.arpa for a /24 network like could be
> populated with ~256 PTRs, but if one has a /29 (say), and fills it
> with their ~8 PTRs, named will return NXDOMAIN for the other
> addresses.  I know that CIDR doesn't use the normal 3.2.1.in-addr.arpa
> but rather something like 128/29.2.1.in-addr.arpa, but that's not a
> master zone.
> 
> It's possible to use a 3.2.1.in-addr.arpa zonefile with some $GENERATE
> lines [re]delegating everything besides the /29 back to the ISP, but
> then one has to hardcode their NS data, which is unfortunate.  The
> only other alternative I can see is to create a separate zonefile for
> each IP.
> 
> Is there a better way, or is it just accepted to let named do the
> lookups (at least the most significant octets' NS might well be
> cached), even for local IPs?
> 
> Thanks,
> Justin

	If you have 1.2.3.128/29 then you should be a slave for
	3.2.1.in-addr.arpa and a master for 128/29.3.2.1.in-addr.arpa
	assuming you are following RFC 2317.

	3.2.1.in-addr.arpa will be administered by you ISP and have
	the CNAMEs pointing in to 128/29.3.2.1.in-addr.arpa to allow
	reverse lookups to work.

	If you don't want to, or can't, follow RFC 2317 then create
	a IN-ADDR.ARPA zone for each individual address.

	zone "128.3.2.1.in-addr.arpa" {
		type master;
		file "128.3.2.1.in-addr.arpa";
	};

	zone "129.3.2.1.in-addr.arpa" {
		type master;
		file "129.3.2.1.in-addr.arpa";
	};

	....
	
	129.3.2.1.in-addr.arpa:
	$TTL 3600
	@	SOA	<namserver1> ...
	@	NS	<namserver1>
	@	NS	<namserver2>
	@	PTR	<hostname>

	Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org