go
mbox1.it-driften.se has one IP number , which also has a corresponding reverse pointer. 3xl.se and sli.se use this as a mailserver. it-driften.se is a domain controlled by two nameservers at wasadata.com. They are on the same IP network. Incoming mail for it-driften.se is handled by two mailservers also at wasadata.com. They are on different IP networks. it-driften.se has one IP number. mbox1.it-driften.se is hosted on a server in Sweden.

mbox1.it-driften.se
a records
 
+ 213.132.99.141 213.132.96.0/19 AS12552 -
+ --- -

it-driften.se
a records
 
+ 193.15.177.83 193.12.0.0/14 AS1257  
+ ---  
ns records
dns2.wasadata.com
+ 193.15.177.98 193.12.0.0/14 AS1257 -
+ --- -
websrv1.wasadata.com
+ 193.15.177.99 193.12.0.0/14 AS1257 -
mx records
smtp1.wasadata.com
+ 193.15.177.90 193.12.0.0/14 AS1257  
+ ---  
smtp2.wasadata.com
+ 85.8.30.7 85.8.0.0/18 AS44581  
ip numbers of host
213.132.99.141
ptrs of ip numbers
mbox1.it-driften.se
ip numbers using ptr to this host
213.132.99.141
domains using this as mailserver
3xl.se
sli.se