go
mx.snc1.tfbnw.net has one IP number , which also has a corresponding reverse pointer. mxrr.tfbnw.net and mx-out.facebook.com point to the same IP. facebook.com, m.facebook.com and publists.facebook.com use this as a mailserver. mx.snc1.tfbnw.net is hosted on a server in United States.

mx.snc1.tfbnw.net
a records
 
+ 69.63.179.26 69.63.176.0/21 AS32934 -
+ --- -
ip numbers of host
69.63.179.26
ptrs of ip numbers
mx.snc1.tfbnw.net
ip numbers using ptr to this host
69.63.179.26
hostnames sharing ip with a-records
mx-out.facebook.com
mxrr.tfbnw.net
domains using this as mailserver
facebook.com
m.facebook.com
publists.facebook.com
domains using this as mailserver under another name
fbookpics.com
fbtest.devekus.com
mx-out.facebook.com
tfbnet.net
tfbnw.com
tfbnw.net
nameservers missing in zone
ns2.tfbnw.net