ah.scd.yahoo.com, w1.scd.yahoo.com, rd.scd.yahoo.com, ac.scd.yahoo.com, 86.scd.yahoo.com and at least 100 other hosts are subdomains to this hostname. yahoo.com is delegated to five nameservers, however two extra nameservers are listed in the zone. All nameservers are at yahoo.com themselves. All of them are on different IP networks. Incoming mail for yahoo.com is handled by six mailservers having a total of eight IP numbers. Some of them are on the same IP network. yahoo.com has three IP numbers. All of them are on different IP networks.