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ButlerianJihad • today at 11:52 AM • 1 reply • view on HN

One of the craziest aspects of IPv6 implementation is the reverse DNS lookups.

IPv6 uses ip6.arpa and segments each little nybble into a subdomain!

https://en.wikipedia.org/wiki/Reverse_DNS_lookup#IPv6_revers...

This means there are always 32 octets to a reverse-IPv6 address, and there are no shortcuts or macros to overcome this! That means if you wish to assign a singular name that maps from a legitimate /64 Network ID, you must populate 64 bits worth of octets in a zone with this data. It is an absurd non-solution. This never should've been allowed to happen, but it will basically mean that ISPs abandon reverse DNS entirely when they migrate to IPv6 implementations.

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Dagger2 • today at 12:41 PM

  $ dig -x 2606:7100:1:67::26 | grep PTR
  ;6.2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.7.6.0.0.1.0.0.0.0.0.1.7.6.0.6.2.ip6.arpa. IN PTR
Run this, then copy/paste the output into your zone file. Remove the ; and add "example.com." or whatever to the end.

I agree it's a pain to read, mostly because DNS addresses are written backwards, but an "absurd non-solution"? For a set of instructions that don't even depend on the format of the record (they work for v4 too), and which I could describe in one line in a HN comment?

If this is the craziest part of v6 then it must be incredibly well designed overall.

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