[ih] MX and A records

[Paul Vixie]

John Levine wrote:
> MX records were invented in 1986 in RFCS 973 and 974, replacing MD and
> MF and as far as I can tell obsoleting MB, MG, and MR.
>
> It looks like there wasn't a rule to fall back to A if there were no
> MD and MF, or if there was it didn't make it into the RFC.  RFC 974
> does describe fallback from MX to A.
>
> Was that expected to be a transitional thing until MX was more widely
> implemented, or was it expected to be permanent?  Or didn't anybody
> think about it either way?

my memories say, MX was designed to draw email traffic away from your A
RR, and if you didn't need to do that, you didn't need an MX RR, either
then or for all time.