asp.bt.com is a domain controlled by four nameservers at bt.com. All of them are on the same IP network. bt.com, bt.co.uk, de.bt.com, crm.bt.com, rio.bt.com and at least 25 other hosts share nameservers with this domain. www.asp.bt.com are subdomains to this hostname. bt.com is a domain controlled by four nameservers also at bt.com. All of them are on the same IP network. Incoming mail for bt.com is handled by five mailservers at intersmtp.com. All of them are on the same IP network. bt.com has one IP number.