ns1.pbi.net has one IP number , which also has a corresponding reverse pointer. blackandassoc.com point to the same IP. qsii.com, wmss.org, irwd.com, mcera.com, mcera.net and at least 100 other hosts use this as a nameserver. blackhole.netfixer.net use this as a mailserver. postmaster.ns1.pbi.net are subdomains to this hostname. pbi.net is a domain controlled by two nameservers at pbi.net themselves. They are on the same IP network. Incoming mail for pbi.net is handled by two mailservers having a total of six IP numbers. There are six duplicated IP numbers. Some of them are on the same IP network. ns1.pbi.net is hosted on a server in United States.