A domain is available only when a registrar-backed search says it can be registered now. DNS and RDAP can reveal use or registration records, but neither confirms a purchasable name or its price.
A DNS lookup is not an availability check
DNS answers one question: where should traffic for this name go? A domain can be registered and have no DNS records, or have records that are temporarily broken. “No website” therefore does not mean “available to register.”
RDAP shows registration data, not a purchasable quote
ICANN Lookup uses RDAP to retrieve current registration data from registries and registrars. That is useful for checking an existing registration and its sponsoring registrar. It is not a shopping cart, does not reserve a name and does not establish the price a registrar will charge.
The registrar is the transactional source of truth
A registrar-backed search asks the system that can actually submit the registration. A useful result includes more than a yes or no: exact domain, availability, registration price, renewal price, currency, minimum term, premium status, source and timestamp.
The result is still a snapshot. Another buyer can register the name before checkout, and registry or premium pricing can change. A fresh quote and a successful registrar response are required.
What to show when a name is taken
“Unavailable” should not be a dead end. A useful search keeps the original intent and returns priced alternatives: a different extension, a concise modifier, or a close spelling that remains readable. Every suggestion needs its own live availability and price rather than an inferred badge.