<p><br>
On Aug 11, 2011 3:09 AM, "Mike Jones" <<a href="mailto:mike@mikejones.in">mike@mikejones.in</a>> wrote:<br>
><br>
> On 11 August 2011 10:15, Erik Kline <<a href="mailto:ek@google.com">ek@google.com</a>> wrote:<br>
> > Certainly I and others have thought of writing our own auto-PTR<br>
> > response generator for delegated reverse zones. I see now that the<br>
> > success of a PTR-verification scheme depends on ISPs *not* doing this<br>
> > for every J. Random Customer.<br>
> ><br>
><br>
> I personally feel that the era of "all hosts should have meaningless<br>
> reverse DNS" should be left as a historical IPv4 practice and not<br>
> brought forward to IPv6 as the only real benefit such automatic<br>
> records serve is saving you spending 5 seconds doing a whois lookup</p>
<p>+1</p>
<p>I like the idea of reverse only being for systems that are in the legitmate control of the domain, ie ...not joe random subscriber of an isp.</p>
<p>I do think the lack of reverse helps give reputation information about the host.</p>
<p>> for find a users ISP, but if you have a reason to look up an IP<br>
> address then you'll do a whois lookup anyway even after looking at the<br>
> hostname. Unfortunately it only takes a few ISPs doing this for other<br>
> people to be forced to accept it. Of course routers (looking at your<br>
> employer here!) and servers should still be set up with proper entries<br>
> as they serve useful diagnostic purposes.<br>
></p>
<p>+1 this is reverse providing good info that builds reputation. </p>
<p>> Perhaps this needs a multi-stage system, reject mail from hosts with<br>
> no reverse DNS then test for the presence of "mail" or "smtp" etc in<br>
> the hostname and factor this in to spam filters, so<br>
> "<a href="http://185479346345.customer542345.example.net">185479346345.customer542345.example.net</a>" starts off with a higher<br>
> spam rating than "<a href="http://mail.example.net">mail.example.net</a>"?<br>
><br>
> I am not keen on a requirement that mail servers should be given a<br>
> specific mail-related hostname, however it is a possible solution to<br>
> consider with IPv6 where it is a lot easier to add additional<br>
> service-specific addresses to a box (assuming the MTA has an option to<br>
> bind to a specific address for outbound connections, i've not checked<br>
> if common ones do).<br>
><br>
> - Mike<br>
</p>