Registry Objects

Nominet uses standard object models within its registries conforming to the relevant RFCs. Below is the information on contact, host and domain objects that registrars will need to register and manage domains.

A unique Repository Object Identifier (ROID) will be assigned to all objects by the registry at time of creation. The ROIDs all follow the regular expression



  • (\\w|_){1,80}  is D, C or H depending on whether it is a <domain:roid>, a <contact:roid> or a <host:roid> respectively followed by a unique string
  • w{1,8} is the gTLD in upper case i.e. WALES or CYMRU

Contact objects

Contact objects reference the information relevant to various contacts associated with a domain name. We support the four standard types of contact:

  • registrant
  • admin
  • technical
  • billing

Our contact objects have the following properties:

  • Adhere to RFC 5733 (Hollenbeck, RFC5733, 2009)
  • A domain name must have exactly one registrant contact at all times. Admin, billing and technical contacts are optional
  • Contact objects can be updated without incurring a fee
  • Proxy contacts will be allowed on domains e.g. for privacy purposes
  • Registrar supplied contact IDs must be unique. A registrar could prefix the ID with a unique string to ensure there are no clashes with other registrar contact IDs
  • Registrar supplied contact IDs must use ASCII characters only
  • Contact ROIDs will be allowed to be shared across multiple domain names
  • ISO Country codes will be required

Host objects

Host objects reference the information about name servers that may be associated with domains. Host objects have the following properties:

  • Adhere to RFC 5732 (Hollenbeck, RFC5732, 2009)
  • Nominet supports host objects and not host attributes
  • A host object is not required to register a domain name although it will not resolve if at least one is not associated with it
  • IPv6 addresses are supported
  • IP addresses must be distinct per host object
  • Hosts can be renamed
  • Host objects can be updated by the owner of the superordinate domain when that name server is linked to another domain

Domain objects

Domain objects reference the information about domains themselves such as status values. Domain objects have the following properties:

  • Adheres to RFC 5731 (Hollenbeck, RFC5731, 2009)
  • Maximum label length is 63 characters specified in RFC 2181 (Elz, 1997)
  • May be registered for a minimum of 1 and a maximum of 10 years in integer multiples of 1 year

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