Prior to 25 June 2011, a query for an IP address in the ARIN region would return with that assignment/allocation within the ARIN region, and a query in the ARIN region for an IP address with no assignment/allocation would result in a “no match” response. On 25 June, a change was misapplied. The intent of this change was to return ARIN’s /8 for IP queries within ARIN’s region for which there is no assignment/allocation, a behavior meant to align ARIN’s Whois output with that of the other RIRs. However, this change introduced an unintended behavior of returning ARIN’s /8, in addition to the desired results, in responses where IP addresses had been assigned or allocated. This change in behavior has created some confusion. On 2 October, ARIN will reinstate the previous behavior for Whois IP queries so that results are returned the way they were before 25 June. ARIN has provided two examples of a Whois query for reference: one with ARIN's /8 returned in the result set hierarchy, and one without ARIN's /8 returned in the result set.
Whois-RWS behavior will not change as it was not affected by the configuration change made on 25 June.
We apologize for any confusion this has caused.