WHOIS & RDAP Reference: Explained

WHOIS & RDAP Reference Explained

Cheatsheet for domain registration data: the WHOIS-to-RDAP shift, RDAP query paths, response fields, common EPP status codes, and the IANA bootstrap.

Registration data moved from WHOIS (TCP port 43, free text) to RDAP (HTTPS, structured JSON). This reference covers the protocol shift, the RDAP query paths, the fields you get back, the status flags you will see, and how a client finds the authoritative server. Pair it with the WHOIS & RDAP Lookup tool to run live queries.

31 of 31 rows


Protocol: WHOIS → RDAP
	RFC 3912 (2004) — TCP port 43, plaintext	The legacy protocol. Unstructured free-text output.
	RFCs 7480–7485 (2015) — HTTPS, JSON	The official successor. Structured, secure, web-native.
	TCP 43 (cleartext) → HTTPS (TLS)	RDAP encrypts the query in transit; WHOIS does not.
	Free text → structured JSON (RFC 7483)	One parser works for every TLD instead of one per registry.
	Impossible → native	RDAP recommends CORS (RFC 7480 §5); a browser can query a registry directly.
	Optional → required for gTLDs	ICANN has required RDAP for all gTLD registries and registrars since 2019.
RDAP query paths
	/domain/<domain>	Example: /domain/example.com
	/ip/<address>	Example: /ip/192.0.2.1 or /ip/2001:db8::1
	/autnum/<asn>	Example: /autnum/13335 (drop the AS prefix)
	/entity/<handle>	A registrar, registrant, or contact by handle.
	/nameserver/<host>	A fully-qualified nameserver host.
Key response fields
	Object type	domain \| ip \| autnum \| entity \| nameserver
	Name in LDH (ASCII) form	e.g. EXAMPLE.COM. unicodeName carries the IDN form.
	EPP status flags	client/server prohibition, hold, pending, etc.
	Lifecycle milestones	registration, expiration, last changed, transfer — each with a date.
	Contacts, each with roles[]	registrar, registrant, abuse, technical, administrative.
	Delegated nameservers	ldhName and/or hostName per entry.
	DNSSEC signing state	delegationSigned: true means the zone is signed.
Common status codes (EPP)
	Transfer locked by registrar	The registrant opted out of registrar transfers.
	Updates locked by registrar	No changes to the record are permitted.
	Deletion locked by registrar	The domain cannot be deleted.
	Transfer locked by registry	A registry-level transfer hold.
	Deletion locked by registry	Registry-level protection against deletion.
	DNS resolution suspended	The domain is removed from the zone — it stops resolving.
	Initial registration window	Typically the first 5 days after registration.
	Post-expiry auto-renew window	Grace period during which the domain auto-renews.
	Deleted, recoverable for a fee	After deletion, a short window to restore the domain.
IANA RDAP bootstrap (server discovery)
	TLD → RDAP server	data.iana.org/rdap/dns.json
	IPv4 range → RIR	data.iana.org/rdap/ipv4.json
	IPv6 range → RIR	data.iana.org/rdap/ipv6.json
	ASN range → RIR	data.iana.org/rdap/asn.json