We pick b.root-servers.net, one of the 13 root servers (1), and ask it about yahoopersonals.com and learn that com is delegated to 13 name servers (2), so we ask b.gtld-servers.net where we learn that yahoopersonals.com is delegated to five name servers, including ns4.yahoo.com (3), so we ask that one and get the following answer:
The five name servers ns1, ns2, ns3, ns4 and ns5.yahoo.com together
Three quarter of the more than hundred domains that use name server group 1 point to the two IP numbers 68.180.206.184 and 98.139.102.145 together, hereafter referred to as "IP group 1", (example: dlsyahoo.com, emailyahoomail.com and findchatingyahoo.com ). Worth noting is that most of the host names that point to IP group 1 use name server group 1.
The mail server. Only
There are about eighty domains that only use the mail server ..