go
rav.nic.uk has one IP number , which also has a corresponding reverse pointer. nic.uk use this as a mailserver. nic.uk is a domain controlled by eleven nameservers at nic.uk themselves. All of them are on different IP networks. Incoming mail for nic.uk is handled by two mailservers also at nic.uk. They are on different IP networks. rav.nic.uk is hosted on a server in United Kingdom.

rav.nic.uk
a records
 
+ 213.248.201.120 213.248.192.0/19 AS8683 -
+ --- -

nic.uk
ns-soa records
ns1.nic.uk
+ 195.66.240.130 195.66.224.0/19 AS5459 -
+ --- -
ns records
ns1.nic.uk
+ 195.66.240.130 195.66.224.0/19 AS5459 -
+ --- -
ns2.nic.uk
+ 217.79.164.131 217.79.164.0/23 AS16260 -
ns3.nic.uk
+ 213.219.13.131 213.219.0.0/18 AS15830  
+ ---  
ns4.nic.uk
+ 194.83.244.131 194.80.0.0/14 AS786 -
+ --- -
ns5.nic.uk
+ 213.246.167.131 213.246.128.0/18 AS8586 -
ns6.nic.uk
+ 213.248.254.130 213.248.254.0/24 AS43519 -
ns7.nic.uk
+ 212.121.40.130 212.121.40.0/24 AS12536  
+ ---  
nsa.nic.uk
+ 156.154.100.3 156.154.100.0/24 AS12008 -
+ --- -
nsb.nic.uk
+ 156.154.101.3 156.154.101.0/24 AS12008 -
nsc.nic.uk
+ 156.154.102.3 156.154.102.0/24 AS12008 -
nsd.nic.uk
+ 156.154.103.3 156.154.103.0/24 AS12008 -
mx records
mx2.nic.uk
+ 195.66.240.114 195.66.224.0/19 AS5459 -
+ --- -
rav.nic.uk
+ 213.248.201.120 213.248.192.0/19 AS8683 -
ip numbers of host
213.248.201.120
ptrs of ip numbers
rav.nic.uk
ip numbers using ptr to this host
213.248.201.120
domains using this as mailserver
nic.uk