Re: Last Call: draft-klensin-rfc2821bis

On Wed, 26 Mar 2008, John C Klensin wrote:
>
> At the time 974 and 1123 were written, the only sort of address record
> in Class=IN was an A RR, and those documents used "A RR" terminology.
> The change in 2821bis essentially substituted the phrase "address
> record" (or "address RR") for "A record" because (i) that seemed to be
> consensus on the list at that time and (ii) there is significant,
> although not universal, existing practice that is consistent with
> treating IPv4 (A) and IPv6 (AAAA) RRs the same way, at least with regard
> to SMTP.
>
> With that change to "address record", if no MX record is found, the SMTP
> client is required to look for DNS names with either A or AAAA RRs,
> rather than A RRs only.

There's also RFC 3974 (Jan 2005, informational) which recommends treating
AAAA like A. The most popular MTAs implement this logic.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
HUMBER: VARIABLE 3, BECOMING SOUTHERLY 4 OR 5. MODERATE. OCCASIONAL RAIN.
MODERATE OR GOOD.
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