On Tue, 12 Sep 2006, Joe Abley wrote:
>
> I've seen many people use "." as part of MX RDATA to indicate that a host
> should not receive mail (e.g. "PRINTER.EXAMPLE.COM. 3600 IN MX 0 ."). I seem
> to remember that meaning is documented informally in Cricket Liu's book, but I
> could be wrong about that (I don't have a copy near the keyboard).

The "no service here" meaning of this kind of "." is explicitly specified
for SRV records. The specification for MX records is more vague, but RFC
2821 does say "If MX records are present, but none of them are usable,
this situation MUST be reported as an error."

Tony.
-- 
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FISHER: WEST OR NORTHWEST 4 OR 5 BECOMING VARIABLE 3 OR 4. FAIR. MODERATE OR
GOOD.
.
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