New Base URL for Reg-RWS on 19 February

Posted: Thursday, 06 February 2020

On 16 July and 30 October of 2019, we announced plans to implement changes to our RESTful API. We noted that these changes might impact the way you interface with ARIN Online for sending reassignment information and receiving reports through ARIN’s Registration RESTful Service (Reg-RWS). The changes are:

  1. The base URL will be no longer be available for Reg-RWS. You must change your base URL to to interface with ARIN’s Reg-RWS service. The base URL has been in place for seven years as the improved way of interfacing with ARIN via Reg-RWS.
  2. ARIN will no longer be supporting TLS 1.0 for Reg-RWS’s transport layer. There are well-known security issues with this protocol. We will continue to support TLS 1.1 and 1.2. Please make sure your client implementation will support TLS 1.1 or 1.2. Read for further details.

The change to TLS support was completed successfully, but some customers were not ready for the change to the Reg-RWS base URL and requested a short delay. In order to allow these customers additional time to update their systems, we reverted that change temporarily.

We will move ahead with changing the base URL to on 19 February following additional outreach to the impacted customers who contacted ARIN. We will send a follow-up confirmation to the community once that change is completed. We strongly recommend that you review your clients that interface with the Reg-RWS service and make any required configuration or code changes.


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