go
webmail.1and1.fr has one IP number , but the reverse is webmailer.1and1.fr. webmailer.1and1.fr point to the same IP. 1and1.fr is a domain controlled by two nameservers at 1and1.fr themselves. They are on the same IP network. Incoming mail for 1and1.fr is handled by three mailservers at schlund.de. All of them are on the same IP network. 1and1.fr has one IP number. webmail.1and1.fr is hosted on a server in Germany even though the hostname implies France.

webmail.1and1.fr
a records
 
+ 212.227.116.98 212.227.0.0/16 AS8560 webmailer.1and1.fr
+ --- webmailer.1and1.fr

1and1.fr
a records
 
+ 212.227.126.71 212.227.0.0/16 AS8560  
+ ---  
ns-soa records
nsa.schlund.de
+ 195.20.224.98 195.20.224.0/19 AS8560 -
+ --- -
ns records
nsa.1and1.fr
+ 195.20.224.98 195.20.224.0/19 AS8560 nsa.schlund.de
+ --- nsa.schlund.de
nsa2.1and1.fr
+ 195.20.244.5 195.20.224.0/19 AS8560 nsa2.schlund.de
+ --- nsa2.schlund.de
mx records
mxintern0.schlund.de
+ 212.227.126.201 212.227.0.0/16 AS8560 mxintern.schlund.de
+ --- mxintern.schlund.de
mxintern1.schlund.de
+ 212.227.126.204 212.227.0.0/16 AS8560 mxintern.schlund.de
mxintern2.schlund.de
+ 212.227.126.205 212.227.0.0/16 AS8560 mxintern.schlund.de
ip numbers of host
212.227.116.98
ptrs of ip numbers
webmailer.1and1.fr
hostnames sharing ip with a-records
webmailer.1and1.fr