I dived recently in the DNS spec, and the MX RR states only a <domain-name> can be there.
But I'm bad at reading RFCs... On section 3.3.9 of the RFC1035 http://tools.ietf.org/html/rfc1035#section-3.3.9 it is specified: 3.3.9. MX RDATA format +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | PREFERENCE | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ / EXCHANGE / / / +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ where: PREFERENCE A 16 bit integer which specifies the preference given to this RR among others at the same owner. Lower values are preferred. EXCHANGE A <domain-name> which specifies a host willing to act as a mail exchange for the owner name. MX records cause type A additional section processing for the host specified by EXCHANGE. On Dec 16, 2013, at 11:26 AM, Murray Kucherawy <[email protected]> wrote: > There's a general but unenforced rule that the thing in an MX record can't > be a CNAME; the MX has to be canonical. > > I have no idea how or why this applies to ADSP, however, since it only > cares about TXT records or the presence of A/MX, not the things to which > they refer. > > On 12/13/13 9:53 AM, "Benny Pedersen" <[email protected]> wrote: > >> John Levine skrev den 2013-12-13 04:00: >>>>> If example.net is a parked domain you can then protect it this way: >>>>> _dmarc.example.net CNAME _dmarc.parked.example.com >>>> >>>> CNAME preserve DNSSEC ? >>> >>> Yes, of course it does. CNAME is a fundamental part of the DNS and >>> always has been. >> >> i have seen CNAME used in MX records, its fundemental it works as >> designed >> >> same problem some domains used in ADSP setup with is now depricated, >> just still used in spamassassin in wild >> >>>> it does not work in ADSP >>> >>> I don't know what you mean by "does not work" here, but it doesn't >>> matter because ADSP is dead, and DMARC does not use it. >> >> MX and ADSP must NOT be ised with CNAME >>
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