We pick k.root-servers.net, one of the 13 root servers (1), and ask it about yahoo.pr and learn that pr is delegated to five name servers (2), so we ask pascal.nic.pr where we learn that yahoo.pr is delegated to two name servers, including ns5.yahoo.com (3), so we ask that one and get the following answer:
Yahoo.pr is a domain controlled by five domain name servers at yahoo.com. All five of them are on different IP networks. Incoming mail for yahoo.pr is handled by one mail server at .. We are missing the IP:s of one server: .. Yahoo.pr has two IP numbers (220.127.116.11, 18.104.22.168). Both are on different IP networks.
The five name servers ns1, ns2, ns3, ns4 and ns5.yahoo.com together
Three quarter of the several thousand of domains that use name server group 1 point to the two IP numbers 22.214.171.124 and 126.96.36.199 together, hereafter referred to as "IP group 1", (example: yahoocoupons.com, yahosex.info and yahoomovie.net ). Worth noting is that three quarter 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 ..