Summary
131.4.204.in-addr.arpa is a domain controlled by four nameservers. Two of them are on the same IP network.
rr.net,
gs.com,
fna.org,
ddb.com,
crl.com and at least 100 other hosts share nameservers with this domain.
4.204.in-addr.arpa is delegated to two nameservers, however both delegated nameservers are missing in the zone and four other nameservers are listed. Two of them are on the same IP network.