IP Cow’s RDAP / Domain Whois tool uses RDAP (Registration Data Access Protocol) — the modern, structured (JSON) successor to classic WHOIS. RDAP is great when it’s available, but not every top-level domain offers it, so some lookups come back empty.
Why some TLDs don’t answer
IP Cow looks each domain up against the IANA RDAP bootstrap registry — the official map of which TLD is served by which RDAP server. If a TLD isn’t in that registry, there’s nowhere to query, and the tool can’t return data.
- gTLDs —
.com,.net,.org, and essentially every new gTLD (.dev,.app,.io-style, etc.) have RDAP — ICANN requires it of its registries. These work. - Many ccTLDs — country-code TLDs (
.de,.uk,.fr,.us, …) run their own registries and many still publish only classic WHOIS, or restrict access, so they’re absent from the RDAP bootstrap. Those return no RDAP data here.
How to check a specific TLD
Open the bootstrap file and search for the TLD — if it’s listed with a service URL, RDAP works for it. The list grows over time as more registries adopt RDAP.
Why we don’t fall back to WHOIS
Classic WHOIS is unstructured free text, rate-limited and inconsistent per registry, and increasingly locked down for privacy. IP Cow stays RDAP-only so results are clean, structured and predictable — we’d rather show you nothing than guess at scraped WHOIS text.