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i.ns.se has one IP number , but the reverse is se1.dnsnode.net. se1.dnsnode.net point to the same IP. se use this as a nameserver. i.ns.se is hosted on a server in Sweden.

i.ns.se
a records
 
+ 194.146.106.22 194.146.106.0/24 AS8674 se1.dnsnode.net
+ --- se1.dnsnode.net
ip numbers of host
194.146.106.22
ptrs of ip numbers
se1.dnsnode.net
hostnames sharing ip with a-records
se1.dnsnode.net
domains using this as nameserver
se