Worth logging a fault with the maintainers of the distro(s)? It seems to be DNAME in reverse V6 may well be useful, albeit as you say not relevant to AS112
On Mon, Oct 14, 2013 at 9:51 PM, Tony Finch <[email protected]> wrote: > Joe Abley <[email protected]> wrote: > > > > Geoff Huston and George Michaelson were kind enough to run an initial > > experiment this week to try and find problems with DNAME support in the > > wild. They did not find any; DNAME support (for the purposes of AS112) > > seems more than adequate. This document (below) includes a description > > of the experiment and the results. > > We are using DNAME for some parts of the University of Cambridge's reverse > DNS. (See below for an example.) We have noticed one quirk and one problem > with this setup, and the problem isn't relevant to AS112. I think it would > make sense for the AS112 project to use DNAME. > > The quirk occurs on Linux, where glibc moans in syslog that it doesn't > understand TYPE39 or DNAME (it varies depending on the version). Often the > messages will come from nscd. However the resolver nobly soldiers on and > handles the synthesized CNAME correctly. Example log message: > > Oct 14 07:52:46 ppsw-33 nscd: gethostby*.getanswer: > asked for "8.255.232.128.in-addr.arpa IN PTR", got type "DNAME" > > The problem is that some mail servers check that the sender has a PTR > record, but choke on DNAME records in the answer. This is only a problem > if you have a server sending mail from an IP address with DNAME reverse > DNS, which is not the case for AS112. > > > ; <<>> DiG 9.9.4rc1 <<>> +noauthority +nostats -x 128.232.232.252 > ;; global options: +cmd > ;; Got answer: > ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43769 > ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1 > > ;; OPT PSEUDOSECTION: > ; EDNS: version: 0, flags:; udp: 4096 > ;; QUESTION SECTION: > ;252.232.232.128.in-addr.arpa. IN PTR > > ;; ANSWER SECTION: > 232.232.128.in-addr.arpa. 1d IN DNAME 232.232.128.in-addr.arpa.cam.ac.uk. > 252.232.232.128.in-addr.arpa. 1d IN CNAME > 252.232.232.128.in-addr.arpa.cam.ac.uk. > 252.232.232.128.in-addr.arpa.cam.ac.uk. 1d IN PTR > gw-257.route-opress.net.cam.ac.uk. > > > Tony. > -- > f.anthony.n.finch <[email protected]> http://dotat.at/ > Forties, Cromarty: East, veering southeast, 4 or 5, occasionally 6 at > first. > Rough, becoming slight or moderate. Showers, rain at first. Moderate or > good, > occasionally poor at first. > _______________________________________________ > DNSOP mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/dnsop >
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