2 A records for a single 1 IP, why not?

[Barry Margolin]

In article <2e0ZOa=5cdytqQg94c9O083wJxFD at 4ax.com>,
Dave Lers  <davelers at home.com> wrote:
>I was chatting with someone who said "multiple A records is
>acceptable" (he's got A records for ns1.domain.com and domain.com
>using the same IP) Now I know it won't make it past nslint but why it
>is a 'bad thing'?

While I recommend using CNAME records instead whenever feasible, I've never
heard it was a bad thing.  It sounds like the author of nslint disagrees,
but that's just his opinion.

>Reverse lookups come to mind but I wonder about their importance as my
>reverse resolves to a subdomain of my ISP, not my domin, and that
>doesn't appear to cause any problems. 
>
>My sub question is what, if any, limitations do I have with a reverse
>that doesn't resolve to my domain.?

I think I've heard of some SMTP servers that have been configured to
require that the reverse lookup point to the same name as in the HELO
greeting.  As far as I'm concerned, that's a bogus requirement.  Not only
would it screw you, but it also screws machines with multiple NICs; the
source IP address of the connection will depend on which NIC is used, but
the HELO name will generally be the same (it comes from the mailer's
configuration file).

-- 
Barry Margolin, barmar at genuity.net
Genuity, Burlington, MA
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