We pick j.root-servers.net, one of the 13 root servers (1), and ask it about accountcreateemailsyahoo.com and learn that com is delegated to 13 name servers (2), so we ask k.gtld-servers.net where we learn that accountcreateemailsyahoo.com is delegated to five name servers, including ns5.yahoo.com (3), so we ask that one and get the following answer:
All of the several thousand of domains that use the mail server . use only the mail server . (example: azizah.com, kscars.com and songshome.com ).
The five name servers ns1, ns2, ns3, ns4 and ns5.yahoo.com together
Two thirds of the several thousand of 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: yahootom.com, yahooansewres.com and yahoo-forum.net ). 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 several thousand of domains that only use the mail server ..