Before ICANN approved of the biz top-level domain in the official DNS root, similar domains of the same name were already in use by alternative DNS roots. This created the possibility of a biz domain pointing to different IP addresses depending on the specific DNS configuration of a client computer. For this reason, the domain's registry, NeuStar, requires that a DNS server be officially registered with them on their list of approved DNS servers before a domain registrar may register it in the WHOIS database.