In article <200503152040.j2FKe8p8001524@host122.r-bonomi.com> you write:
From owner-nanog@merit.edu Tue Mar 15 14:12:12 2005 Date: Tue, 15 Mar 2005 15:12:10 -0500 From: Robert Blayzor <rblayzor@inoc.net> To: alex@pilosoft.com Cc: Mike Sawicki <fifi@HAX.ORG>, nanog@merit.edu Subject: Re: Delegating /24's from a /19
alex@pilosoft.com wrote:
Either by doing DNS delegation on the zone boundary or by SWIP'ing the space to the other company.
You can SWIP it yes, but that won't help DNS on small blocks like /24's.
It is very easy to do DNS delegation, say if you have 128.0.0.0/19, and you want to delegate 128.0.1.0/24, in your zone file for 0.128.in-addr.arpa zone put
1 IN NS ns1.othercompany.com 1 IN NS ns2.othercompany.com
The only way it will work is to use RFC2317 or slave the zones from the other name server. Because he does not have the entire /16 you can't just delegate like that.
OK, what am I missing?
*ASSUMPTION*: The holder of the /16 _has_ delegated rDNS for the 32 /24s to the /19 owner.
The /19 owner can, on it's nameserver, run an "authoritative" zone for the /16 -- with _its_ /24s listed explicitly, and a wildcard pointing back to the rDNS nameserver of the /16 owner.
"He who" queries from the outside world will work their way down from the .arpa zone, to the X.W.in-addr.arpa zone, get referred to the nameserver at "thiscompany", and get referred to the NS listed for Y.X.W.in-addr.arpa. which will resolve Z.Y.X.W.in-addr.arpa.
"He who" queries the /19 owner nameserver directly for a Y.X.W.in-addr.arpa address that lies within the /19 owner's addresses will get answered by that nameserver, *or* be referred to the client's server. If they ask for something *outside* the /19 owner's space, the wildcard -- referring to the 'upstream' (the /16 owner) nameserver kicks in.
_AS_LONG_AS_ the 'delegated to' nameserver has the wildcard in it pointing back to the 'parent' nameserver, this seems to work just fine. Admittedly, if the upstream block owner changes the _name_ of it's nameserver(s), the 'delegated to' nameserver requires manual tweaking, but, realistically, "how often" does _that_ happen?
This is the worst piece of "advice" I have ever seen. SWIP the nameservers. The OP customers will be expecting to be able to use the X.Y.Z.IN-ADDR.ARPA as the zone name. It also reduces the number of nameservers involved. It is also the clean solution. The RIR's are all setup to handle this. For those advising RFC 2317 please read the first sentence of the introduction. RFC 2317 was NOT written to cover this situation. Go put it back in the filing cabinet and bring it out when you have a situation that it does cover (/25-/32 sub-delegation). Mark