Summary
12.90.193.in-addr.arpa is delegated to two nameservers, however one extra nameserver is listed in the zone. All of them are on different IP networks.
kq.no,
ij.no,
una.py,
mef.no,
eg.net and at least 100 other hosts share nameservers with this domain.
90.193.in-addr.arpa is a domain controlled by three nameservers. All of them are on different IP networks.