[dns-operations] fewer PTRs plz (Re: reverse DNS for DHCPV6 and PD's)

Paul Vixie vixie at vix.com
Mon Jun 13 05:33:51 UTC 2011

fw at deneb.enyo.de (Florian Weimer) writes:

>> IOW, the network operations community should work with the email server
>> operations community on this.
> Why?
> If it's a mandatory protocol element, it presence does not carry any
> information at all. 8-)

it wasn't mandatory until rick adams hacked ftp.uu.net to reject connections
from places that had no PTR.  that idea caught on, and then some time later
we got hundreds of millions of dsl/cable/mobile/etc connected users, most of
whom do not have useful PTR's (201-41-169-85.ctaje701.dsl.brasiltelecom.net.br
is an example of what i mean by non-useful.)

i urge an end to autogenerated PTRs.  web servers won't care, e-mail servers
sometimes will, and nobody uses FTP much.  make a PTR part of a "business
grade" service.   let the rest of us use the absence of a PTR as evidence
that high valued services like reaching our tcp/25 server should not work.

i say this knowing that a lot of folks are wondering what to do with PTR's
for IPv6, and i know we wrote RFC 2136 with this use in mind, but... "don't."
just don't.  just leave the PTR space blank for consumer grade connections.
Paul Vixie

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