IPv6 automatic reverse DNS
baldur.norddahl at gmail.com
Fri Oct 28 23:02:57 UTC 2016
Many service providers have IPv4 reverse DNS for all their IP addresses.
If nothing is more relevant, this will often just be the IPv4 address
hashed somehow and tagged to the ISP domain name. For some arcane reason
it is important to have the forward DNS match the reverse DNS or some
mail servers might reject your mails.
However with IPv6 it is not practical to build such a complete reverse
DNS zone. You could do a star entry but that would fail the
reverse/forward match test.
It should be simple to build a DNS server that will automatically
generate a hostname value for every reverse lookup received, and also be
able to parse that hostname value to return the correct IPv6 address on
Does any DNS server have that feature? Should we have it? Why not?
I know of some arguments for:
1a) mail servers like it
1b) anti spam filters believe in the magic of checking forward/reverse
2) traceroute will be nicer
3) http://ipv6-test.com/ will give me 20/20 instead of 19/20 (yes that
was what got me going on this post)
4) Output from "who" command on Unix will look nicer (maybe).
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