RDAP bootstrap

RDAP bootstrap is how a client finds the right server for a domain. There is no single RDAP database. Each registry runs its own service, and IANA publishes the map from top-level domain to base URL.

The whole procedure is three steps:

1. Fetch https://data.iana.org/rdap/dns.json.
2. Find the entry whose list of top-level domains contains yours.
3. Append domain/{name} to the base URL in that entry and request it.

The file is a JSON document of [[tlds], [urls]] pairs with a publication date. Cache it. It changes when a registry moves, which is rarely, and fetching it on every lookup wastes a request on a file that is identical all week.

What about rdap.org

rdap.org is a redirect service, not a database. It answers a request with a 302 to the authoritative server, which is convenient for a shell one-liner and wrong for a program: it adds a hop, a dependency and a rate limit that nobody promised you.

Bootstrap yourself. It is one cached file and one lookup.

What Domduck records

Domduck resolves each domain through the IANA registry and stores the registration reading, not the bootstrap step. The base URL that answered is kept with the raw response, so a reading can be checked against the server that produced it years later.

Not every top-level domain is in the file. Generic ones are required to serve RDAP, and many country ones do not, so a bootstrap miss is a real answer meaning "this registry publishes no RDAP service", not an error to retry.

Why it matters

A client that hardcodes one server works until the first domain outside that registry. A client that uses a redirect service works until the service is slow. The registry file is the only route that is defined by a specification and answers for every top-level domain that has a service at all.