On Sat, 14 Feb 2004, Alex van den Bogaerdt wrote:
I used to be opposed to the idea of having an MX record as a MUST. Today
I'm not so sure anymore.
So, for starters, what about these (the concept, not the text please):
[SNIP]
- The resulting addresses MUST have PTR records, and these PTR records
MUST match the host. The following lookups will still work but are
discouraged:
somehost -> a.b.c.d; a.b.c.d -> otherhost; otherhost -> a.b.c.d
This is absolutely standard setup for many places. domain.com => a.b.c.d
=> mailhost.comain.com => a.b.c.d. This happens because domain.com might
be needed as a www or telnet server, and this might be on a separate
system to the MX. I've always considered it peculiar that DNS specified
what is effectively a TCP redirect for port 25, but it does, and that's
how it's used.
The following will NOT result in a valid lookup:
somehost -> a.b.c.d; a.b.c.d -> otherhost; otherhost -> p.q.r.s
These last conditions are naturally required of any DNS-based lookup.
S.
--
Shevek http://www.anarres.org/
I am the Borg. http://www.gothnicity.org/