[dns-operations] MX record definition?
sm at resistor.net
Wed Dec 17 23:41:56 UTC 2008
At 15:21 17-12-2008, Seth Mattinen wrote:
>Does anyone know offhand where the MX record is defined? The best I
>can find is section 3.3.9 in RFC 1035. I'm trying to find a
>reference that says numeric MX records are bad. I'm assuming they're
>a no-no, at least that's what I've always been told.
Section 5.1 of RFC 5321 explains how the SMTP client does address
resolution and mail handling. Quoting that RFC:
When a domain name associated with an MX RR is looked up and the
associated data field obtained, the data field of that response MUST
contain a domain name. That domain name, when queried, MUST return
at least one address record (e.g., A or AAAA RR) that gives the IP
address of the SMTP server to which the message should be directed.
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