[dns-operations] Alternate IPv6 address to hostname mapping, Re: IPv6 PTR records

Mark Scholten mark at streamservice.nl
Wed Dec 22 17:16:07 UTC 2010

> -----Original Message-----
> From: dns-operations-bounces at lists.dns-oarc.net [mailto:dns-operations-
> bounces at lists.dns-oarc.net] On Behalf Of Paul Vixie
> Sent: Wednesday, December 22, 2010 5:03 PM
> To: dns-operations at mail.dns-oarc.net
> Subject: Re: [dns-operations] Alternate IPv6 address to hostname
> mapping, Re: IPv6 PTR records
> > Date: Wed, 22 Dec 2010 22:07:35 +0900
> > From: Randy Bush <randy at psg.com>
> >
> > > PTR has an impedence mismatch with IPv6
> >
> > perhaps this deserves a bit of amplification
> ok.  in ipv4 there's been a long standing problem in that the A/PTR
> model
> for host name->addr and addr->name did not take broadband into account,
> it
> came from a time when hosts were rare and the name/address bindings
> were
> mostly static.  some work went into dns dynamic update + dhcp
> integration
> but has had very little impact on most hosts which are broadband
> accessors.
> since some internet transaction forms require addr->name bindings and
> since
> there was no other way to create them, access providers depend on
> things
> like $GENERATE to create a lot of pro forma PTR's just to have matching
> A/PTR.  this was an unpleasant workaround but the design tolerated it.
> in IPv6 the same pressures exist but that workaround does not work
> anymore.
With some name servers (at least PowerDNS) you could create a script that
generates the PTR/AAAA record on the fly (after checking for static
configured PTR/AAAA records). Isn't that a good option for this "problem"? I
also only like to require it for emails, from a mail server to another mail
server (as it limits some abuse). For mail clients to mail servers it is
also possible to use some authentication options.

Regards, Mark

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