Now Available: Whois-RWS Differences Documentation

Posted: Friday, 11 June 2010

ARIN is deploying an improved Whois service called Whois-RWS on 26 June 2010. When using the Whois-RWS you will notice some differences in behavior for certain queries and corresponding result sets on the NICNAME/WHOIS port 43 service. Detailed documentation on these differences is now available at:

ARIN’s Directory Service for registration data has used the NICNAME/WHOIS protocol since its inception. The limitations of the NICNAME/WHOIS protocol are well known and documented in RFC3912. Whois-RWS was created as an alternative to the ARIN Whois and will provide much richer functionality and capability to the community.

A demo of this service has been available since October 2009. The demonstration service is available at

ARIN continues to welcome community participation on the Whois-RWS mailing list, and we invite you to subscribe and share your thoughts and suggestions at:

More detailed information on these changes and other future features that may impact the community at ARIN is available at:


Mark Kosters
Chief Technology Officer
American Registry for Internet Numbers (ARIN)