Check modes

Four levels of depth — what each mode queries, what it returns, and how billing follows the method that answered.

Every check — single or bulk — runs in one of four modes. They differ in which sources are queried, what the result contains, and what it costs.

Mode (UI label)	Sources	Returns	Typical latency
Availability Check	In-memory registered-domains index; escalates to a verified lookup on a miss	Available yes/no	Instant on an index hit; otherwise like Verified
Verified	DNS lookup, falling back to RDAP	Available yes/no, verified — "0% false positives"	Well under a second for most domains
Basic Info	RDAP, falling back to WHOIS	Availability + registrar, created / updated / expiry dates	A few seconds
Full WHOIS/RDAP	RDAP, falling back to WHOIS	Everything above + the raw RDAP/WHOIS responses and which servers answered	A few seconds

The cache comes first

Every mode consults DomainRadar's result cache before touching the network — controlled by the cache tolerance you set (in the bulk dialog: always fresh, or reuse results up to 1 hour / 24 hours / 3 days / 7 days old; via the API: any maxAge duration). A cache hit is marked as such on the result and costs no fresh lookup — which is what makes re-running a big list against overlapping candidates cheap. Info and Full only reuse cached results that themselves came from RDAP/WHOIS, so you never get a shallow answer to a deep question.

How each mode behaves

Availability Check

The fastest tier. DomainRadar keeps an in-memory index of registered domains; if your domain is in it, the answer — registered — comes back without any network call. If it's not in the index, the check transparently escalates to the Verified pipeline, so an "available" answer is always network-verified, never probabilistic. (The index is probabilistic in one direction only: with a vanishingly small probability — around 0.000001% — it can report a free domain as registered.)

Best for: huge candidate pools where most domains are taken and you want the taken ones eliminated as cheaply as possible.

Verified

A real DNS lookup (A/AAAA/MX/NS/TXT); if DNS is inconclusive, RDAP settles it. Zero false positives — if it says available, it's available.

Best for: the default. Availability answers you'd act on.

Basic Info

Queries RDAP (the structured successor to WHOIS) directly, falling back to the registry's WHOIS server where RDAP isn't supported. Returns the registrar and the created / updated / expiry dates alongside availability.

Best for: "it's taken — by whom, and when does it expire?"

Full WHOIS/RDAP

Same sources as Basic Info, plus the complete raw RDAP JSON and/or WHOIS text and the exact servers that answered — copyable from the result panel.

Best for: investigations, evidence collection, and anything where you need the unparsed record.

Billing follows the method that answered

Usage is metered by the method that produced your answer — index, DNS, RDAP, or WHOIS — each with its own rate and free-tier allowance. An Availability Check resolved by the index bills at the cheapest rate; one that escalated bills as the method that answered. Cache hits don't trigger fresh lookups. The bulk-check dialog shows a cost estimate with the free tier subtracted before you commit; current rates are on the pricing page.

Per-domain outcomes

A check can end in one of five states (visible in bulk results and the API):

Status	Meaning
`registered`	The domain exists — not available.
`available`	Free to register.
`error`	The lookup failed (malformed response, no RDAP/WHOIS server for the TLD, network error) — the result carries the error message.
`timeout`	The source didn't answer within the 5-second per-source timeout.
`rate_limited`	The registry's WHOIS server rejected the query for rate reasons — retry later.

One failed domain never fails the request or the bulk job around it.

Check a single domain — the Quick Domain Check box.
Bulk checks — the same modes at scale.
Limits and errors — rate limits per endpoint.

Check modes

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