correo.yahoo.com.mx has one IP number , via cname to rc.yahoo.com , but the reverse is w2.rc.vip.re4.yahoo.com. av.com, yahoo.pk, yahoo.sg, yimg.com, yahoo.ca and at least 100 other hosts point to the same IP. yahoo.com.mx is a domain controlled by five nameservers at yahoo.com. All of them are on different IP networks. Incoming mail for yahoo.com.mx is handled by six mailservers having a total of eight IP numbers. Some of them are on the same IP network. yahoo.com.mx has two IP numbers. They are on different IP networks. correo.yahoo.com.mx is hosted on a server in United States even though the hostname implies Mexico.