PTR records for IPv6

David Farmer farmer at
Mon Sep 2 01:46:53 CEST 2013

On 9/1/13 16:30 , Brian E Carpenter wrote:
> So, is there any real operational value in this, or is it just
> a case of "we did it for v4 so it must be right for v6"?
>     Brian

Purely in the context of servers, especially well-know services like 
mail and web, just to name a couple, I think there is some value in 
having PTR records.  PTRs help add some positive reputation and credence 
that you are talking to an authorized service and not just a 
fly-by-night service.  I don't necessarily think this should be required 
for every service, but requiring this for mail servers doesn't seem 
completely out of line, for several reasons mentioned by others.

Also, I would really like to see all routers have at least some generic 
PTR, simply for the sake of traceroute.  And, traceroute itself is a 
reasonable excuse to have PTR records on most well-known services.

However, in IPv4 some have required PTRs even on client and essentially 
every IPv4 address used on the Internet.  I think this has little value 
and would most definitely be a case of "we did it for v4 so it must be 
right for v6", not to mention the fact that /64 for all practical 
purposes is innumerable.

So, I wouldn't want to generically reuse the same operational practices 
for PTRs in IPv6 that we have use in IPv4 up to now, but that doesn't 
mean I think PTR are completely obsolete and I think they have value in 
some situation, this is probably one of them.


> -------- Original Message --------
> Subject: [nznog] Orcon IPv6 rDNS delegation
> Date: Mon, 2 Sep 2013 02:08:47 +1200
> From: Jonathan Spence <jonathan.spence at>
> Reply-To: jonathan.spence at
> To: <nznog at>
> Hi everyone, Google have just started enforcing PTR records for IPv6
> addresses delivering to Gmail. Our IPv6 works great with Orcon but having
> serious issues getting delegation back to our nameservers setup.
> <irrelevant operational details omitted>

David Farmer               Email: farmer at
Office of Information Technology
University of Minnesota
2218 University Ave SE     Phone: 1-612-626-0815
Minneapolis, MN 55414-3029  Cell: 1-612-812-9952

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