Mail is all this discussion is in the context of On Friday, January 11, 2013, Karl Auer wrote:
On Thu, 2013-01-10 at 20:23 +0530, Suresh Ramasubramanian wrote:
Unused space generally gets a $generate type generic scripted runs which could be whatever, like ip-ad-dr-ess.example.com
Nothing that actually stores actual RRs will scale to the number of addresses available in IPv6.
If you want a PTR for every possible address in your network, or even just every possible address in a single /64 subnet then you are SOL as far as IPv6 is concerned. The only way to do it is to fake it - for example by synthesising responses on the fly. You can't cache the synthesised responses either, that would be inviting a DoS.
I said this would be "pointless" because if providing RRs were as simple as synthesising one on request, then the presence of a PTR record would no longer be a meaningful indicator of cluefulness (not that it is now IMHO, but opinions clearly differ on that).
As for v6 how popular do you see it getting for mail?
Well - at least as popular as IPv4 - eventually :-)
Regards, K.
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