Name Entity Administrator[5] Notes IDN DNSSEC SLD IPv6 .com commercial Verisign This is an open TLD; any person or entity is permitted to register. Though originally intended for use by for-profit business entities, for a number of reasons it became the "main" TLD for domain names and is currently used by all types of entities including nonprofits, schools, and private individuals. Domain name registrations may be successfully challenged if the holder cannot prove an outside relation justifying reservation of the name,[citation needed] to prevent "squatting".