[knot-dns-users] What is mod-synthrecord used for?

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-automati… "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? 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. Regards, Michael