Re: RFC 2?821 and CNAMEs
martin f krafft <madduck@debian.org> writes:
> RFC 2821 obsoletes STD-10, and says:
> 3.6 Domains
> Only resolvable, fully-qualified, domain names (FQDNs) are permitted
> when domain names are used in SMTP. In other words, names that can
> be resolved to MX RRs or A RRs (as discussed in section 5) are
> permitted, as are CNAME RRs whose targets can be resolved, in turn,
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> to MX or A RRs.
> ^^^^^^^^^^^^^^^
> Though I guess it gets interesting when we start to look at the
> meaning of "obsoletes":
As someone who was on the RFC 2821 working group and vaguely remembers
this, I seem to recall that this was one of those cases where everyone was
already doing this and it didn't cause interoperability problems, so RFC
2821 backed off the strength of the requirement.
Note, though, that STD-10 is a Standard whereas RFC 2821 is still only a
Proposed Standard. IIRC, formally the obsolete only fully applies once
RFC 2821 reaches the same level in the standards process.
--
Russ Allbery (rra@debian.org) <http://www.eyrie.org/~eagle/>
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