Hey,
On ds., març 29 2025, Michael Grimm via knot-dns-users wrote:
Hi,
given the case that a ip6/xy block might be delegated to me by
my ISP, I began investigating Knot DNS' functionality with
regard to ip6.arpa.
Hereby I stumbled over the module synthrecord and do not really
understand what it is used for.
From
https://www.knot-dns.cz/docs/3.4/singlehtml/index.html#synthrecord-automatic-forward-reverse-records
"Records are synthesized only if the query can't be satisfied
from the zone."
Please excuse my ignorance, but why would/should/must one return
something else than the following for hosts not in the zone?
those are PTR records and are essential for things like email
(learndmarc.com is a good resource that checks for this)
It can also be useful to generate such records under a domain of
the ISP itself, any network tool that uses DNS to resolve
hostnames will show that and it can help separate your own network
from external networks.
As a quick example from this mailing list:
$ host lists.nic.cz
lists.nic.cz has address 217.31.204.208
lists.nic.cz has IPv6 address 2001:1488:800:400::2:208
lists.nic.cz mail is handled by 10 mail.nic.cz.
$ host 2001:1488:800:400::2:208
8.0.2.0.2.0.0.0.0.0.0.0.0.0.0.0.0.0.4.0.0.0.8.0.8.8.4.1.1.0.0.2.ip6.arpa
domain name pointer mailman.nic.cz.
8.0.2.0.2.0.0.0.0.0.0.0.0.0.0.0.0.0.4.0.0.0.8.0.8.8.4.1.1.0.0.2.ip6.arpa
domain name pointer lists.nic.cz.
Cheers,
--
Evilham
kbn> host 2001:dead:beef::1
Host
1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.f.e.e.b.d.a.e.d.1.0.0.2.ip6.arpa
not found: 3(NXDOMAIN)
Any feedback is highly appreciated, thanks.
--
