go
mx.cdc.es has one IP number , but the reverse is 45.red-80-34-83.staticip.rima-tde.net. mx.gasmar.es, mx.gasconymarco.com, mx.canaldirecto.org and 45.red-80-34-83.staticip.rima-tde.net point to the same IP. cdc.es use this as a mailserver. cdc.es is a domain controlled by two nameservers at interferr.com. They are on the same IP network. Incoming mail for cdc.es is handled by one mailserver at cdc.es themselves. cdc.es has one IP number. mx.cdc.es is hosted on a server in Spain.

mx.cdc.es
a records
 
+ 80.34.83.45 80.34.0.0/16 AS3352 45.red-80-34-83.staticip.rima-tde.net
+ --- 45.red-80-34-83.staticip.rima-tde.net

cdc.es
a records
 
+ 82.223.142.41 82.223.0.0/16 AS20718  
+ ---  
ns-soa records
ns1.interferr.com
+ 82.223.142.33 82.223.0.0/16 AS20718 33.142.223.82.arsystel.com
+ --- 33.142.223.82.arsystel.com
ns records
ns1.interferr.com
+ 82.223.142.33 82.223.0.0/16 AS20718 33.142.223.82.arsystel.com
+ --- 33.142.223.82.arsystel.com
ns2.interferr.com
+ 82.223.142.34 82.223.0.0/16 AS20718 34.142.223.82.arsystel.com
+ --- 34.142.223.82.arsystel.com
mx records
mx.cdc.es
+ 80.34.83.45 80.34.0.0/16 AS3352 45.red-80-34-83.staticip.rima-tde.net
+ --- 45.red-80-34-83.staticip.rima-tde.net
ip numbers of host
80.34.83.45
ptrs of ip numbers
45.red-80-34-83.staticip.rima-tde.net
hostnames sharing ip with a-records
45.red-80-34-83.staticip.rima-tde.net
mx.canaldirecto.org
mx.gasconymarco.com
mx.gasmar.es
domains using this as mailserver
cdc.es
domains using this as mailserver under another name
canaldirecto.org
gasmar.es