Similar to how domain names are issued through a domain registrar in the DNS system, Decentralised Address Name Registrars will maintain a registry of Address Names that users have registered through them. In addition to allowing a DARP compliant application to use this registry to verify a DID's ownership of an Address Name, it also serves as the initial lookup source for starting the resolution process of an Address Name entered into the application by one of their users.
While a registry lookup can be used to verify address name ownership, it should still be used in conjunction with a Verifiable Credential issued by a Decentralised Address Name Registrar as this provides a cryptographic proof, which the registry entry doesn't. Not relying solely on the registry for verifying ownership will allow registries to be used in different ways to provide optimisations and greater decentralisation, such as caching or distribution of their hosting.
Although there are currently no constraints on how a Decentralised Address Name Registrar should host a registry it maintains, the DARP team will be exploring peering arrangements that will allow the decentralisation of registries so that a registrar doesn't become a single point of failure.