go
ns-ps.ripe.net has one IP number , which also has a corresponding reverse pointer. ps use this as a nameserver. ripe.net is a domain controlled by four nameservers. All of them are on different IP networks. Incoming mail for ripe.net is handled by two mailservers at ripe.net themselves. They are on the same IP network. ripe.net has one IP number. ns-ps.ripe.net is hosted on a server in Netherlands.

ns-ps.ripe.net
a records
 
+ 193.0.12.169 193.0.12.0/23 AS3333 -
+ --- -

ripe.net
a records
 
+ 193.0.6.139 193.0.0.0/21 AS3333  
+ ---  
ns-soa records
ns-pri.ripe.net
+ 193.0.0.195 193.0.0.0/21 AS3333 -
+ --- -
ns records
sns-pb.isc.org
+ 192.5.4.1 192.5.4.0/24 AS3557 -
+ --- -
sunic.sunet.se
+ 192.36.125.2 192.36.125.0/24 AS1653 -
ns-pri.ripe.net
+ 193.0.0.195 193.0.0.0/21 AS3333 -
ns3.nic.fr
+ 192.134.0.49 192.134.0.0/22 AS2486 -
mx records
postgirl.ripe.net
+ 193.0.19.66 193.0.18.0/23 AS3333 -
+ --- -
postlady.ripe.net
+ 193.0.19.65 193.0.18.0/23 AS3333 -
ip numbers of host
193.0.12.169
ptrs of ip numbers
ns-ps.ripe.net
ip numbers using ptr to this host
193.0.12.169
domains using this as nameserver
ps