bgtops.att.net is a domain controlled by four nameservers. Some of them are on the same IP network. att.net, ave.com, ip.att.net, amlewa.net, my.att.net and at least 42 other hosts share nameservers with this domain. bgtpa01.bgtops.att.net are subdomains to this hostname. att.net is a domain controlled by four nameservers. Some of them are on the same IP network. Incoming mail for att.net is handled by two mailservers at att.net themselves. They are on different IP networks. att.net has one IP number.