In message <alpine.lsu.2.00.1003202112330.2...@hermes-2.csi.cam.ac.uk>, Tony Fi nch writes: > On Sat, 20 Mar 2010, Glenn English wrote: > > > > Just why qmail reports a T_ANY failure as a CNAME failure, I also don't > > know. > > This is a bug in qmail. It tries to canonicalize domains in the SMTP > envelope of outgoing messages. It originally did this by performing CNAME > queries on each domain, but this caused interop problems with BIND 4.
No it didn't. BIND 4 always answered CNAME queries correctly if the zone content was correct. What happened was people didn't correct load errors and a ANY query worked around the fact that they didn't correct the loadtime errors. > The > CNAME query was changed to an ANY query, which is buggy in a number of > ways: ANY queries are much more likely to trigger qmail's undersized DNS > buffer bug; and ANY queries are supposed to be used for debugging not for > normal operations. > > The correct way to canonicalize a mail domain is to do an MX query (or > failing that A and AAAA queries) and if the domain is not canonical the > response will include the CNAME record. > > The reason for canonicalization was conformance with RFC 1123 section > 5.2.2. However when qmail was written this was not necessary for > interoperability and the requirement was removed in the DRUMS process > that yielded RFC 2821. > > So the way to actually fix the bug is to delete the canonicalization code. > > Tony. > -- > f.anthony.n.finch <d...@dotat.at> http://dotat.at/ > GERMAN BIGHT HUMBER: SOUTHWEST 5 TO 7. MODERATE OR ROUGH. SQUALLY SHOWERS. > MODERATE OR GOOD. > _______________________________________________ > bind-users mailing list > bind-users@lists.isc.org > https://lists.isc.org/mailman/listinfo/bind-users -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org _______________________________________________ bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
