From: mouss (moussnetoyen.net)
Date: Fri Apr 18 2008 - 02:13:59 CDT

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Bill Cole wrote:
> At 12:01 AM -0400 4/18/08, Jimbo wrote:
>> TechTalk wrote:
>>>
>>> On 17-Apr-08, at 3:17 PM, mouss wrote:
>>>> PS. why do you have two PTR records for 66.119.164.107?
>>>
>>>
>>> And, as far I can tell I only have one PTR record. The PTR record,
>>> reverse DNS, is maintained by my ISP who controls the IP block.
>>>
>> host 66.119.164.107
>> 107.164.119.66.in-addr.arpa domain name pointer db.anthemfx.com.
>> 107.164.119.66.in-addr.arpa domain name pointer mail.anthemfx.com.
>
> Note that other than making humans (and poorly written software) go
> "HUH?" there is nothing wrong with multiple PTR's.
>
>

There is nothing wrong if you get them right because not much
people/applications would care. But then you have to get them right,
which is not the case here since the "db...." PTR doesn't point back to
the original IP. and if one doesn't need multiple PTRs, why run the risk?

and while we are at this, here is a correct but still problematic one
$ host 76.79.2.40
40.2.79.76.in-addr.arpa domain name pointer rrcs-76-79-2-40.west.biz.rr.com.
40.2.79.76.in-addr.arpa domain name pointer lists.maddoc.com.
40.2.79.76.in-addr.arpa domain name pointer lists.maddoc.net.

(This is the URIBL mailing list server). now 33% of their mail gets
blocked by people who check for generic rDNS (depending on which PTR is
returned).

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