Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!jarthur!nntp-server.caltech.edu!gah From: gah@hood.hood.caltech.edu (Glen Herrmannsfeldt) Newsgroups: comp.protocols.tcp-ip.domains Subject: Re: Subnets and IN-ADDR.ARPA Message-ID: Date: 14 Apr 91 06:21:52 GMT References: <2391727@MVB.SAIC.COM> Sender: news@nntp-server.caltech.edu Organization: California Institute of Technology, Pasadena Lines: 36 Regarding reverse lookups for sub 24bit subnets.... We recently had a similar problem, in that our group was given aouthority for certain addresses on the main network, as well as our own subnets. I wanted reverse lookup authority for those addresses. It was actually 50 addresses. I had the net admin. put in CNAME records, pointing to a subdomain of the applicable in-addr domain. Specifically, origin 4.215.131.in-addr.arpa 151 CNAME 151.hood note that no period after either. This adds the current domain to each entry. I always thouht that the required periods after fully qualified names (such as PTR names) were dumb, but it works nice here. Anyway, then I got authority for hood.4.215.131.in-addr.arpa, and everything works fine. If you want to see it, nslookup set debug set type=ptr 171.4.215.131.in-addr.arpa There was some discussion before doing this, about how fast it was, and whether there were other ways. Since the primary for 215.131.in-addr.arpa is secondary for us, I think it is all cached, anyway. Another suggestion was to put NS records in for all of them. This may have worked, but I was worried about overflowing some table of NS records. named should be designed for lots of CNAMEs, but not necessarily for lots of NS's. Anyway, it works, and no complaints. -- glen