Glossary
RDAP (Registration Data Access Protocol)
RDAP is the modern, structured successor to WHOIS, returning domain and IP registration data as JSON over HTTPS with standardized fields.
RDAP (Registration Data Access Protocol) is the modern replacement for whois. It serves the same registration data — for domains, IP ranges, and asns — but as structured JSON over HTTPS rather than free-form text.
Advantages over WHOIS
- Machine-readable — consistent JSON fields instead of registry-specific text.
- Standardised — defined by the IETF, so all registries respond the same way.
- Secure — runs over
https, with support for differentiated access and authentication. - Referrals — responses link to the authoritative source for the queried object.
Why it matters for hosting
RDAP is now the official protocol ICANN requires registries to support, and whois is being phased out. For tools that look up domain expiry, registrar, or nameserver data programmatically, RDAP's predictable JSON makes results far more reliable to parse and display.
See also
WHOIS
WHOIS is a query protocol that returns registration details for a domain or IP, such as the registrar, nameservers, and creation date.
ASN (Autonomous System Number)
An ASN is a unique number identifying a network of IP ranges under one operator, used by BGP to route traffic across the internet.
IP Address
An IP address is the unique numeric label assigned to each device on a network, used to route data to the right destination across the internet.
DNS (Domain Name System)
DNS is the internet phone book that translates human-readable domain names like example.com into the IP addresses computers use to connect.