ARIN’s RDAP and Whois Services: Getting the Information You Need

You have been using a “Whois” tool for years to look up network-related information at ARIN. (The term “Whois” is a commonly-used term that can have multiple meanings, but we’ve been using it to mean a service ARIN provides for you to get data, such as name and contact information, about people who register a resource like an IP address, ASN, or domain.)

There have been some recent changes at ARIN to our search services, and you might be wondering what tools ARIN now provides to look up public registration data for Internet resources. Here’s a quick primer to let you know about what we offer.

Many of ARIN’s users prefer to use a web-based search tool to get the registration data they need, and we offer two of those: Whois/RDAP and Whois-RWS. These tools are named for their underlying protocols: Registration Data Access Protocol (RDAP) and RESTful Web Service (RWS). This graphic provides a brief overview of the differences between the two:

One of the main benefits of Whois/RDAP is that you can use it to get information about resources managed by all of the other RIRs and domain name registries/registrars that support RDAP—not just those managed by ARIN. (Keep in mind that each RIR and registrar stores data about their resources a little differently, so information retrieved on those resources might vary.) Another RDAP benefit is that it supports “bootstrapping,” which helps your queries get directed to the right place faster. ARIN uses RDAP in its “Combined Search Site or Whois” tool that is located on ARIN web pages, and provides separate RDAP documentation on its site.

ARIN also still provides access to its own registration data using Whois-RWS. Although you can search for information on resources managed by other RIRs, you’ll only receive pointers to those records. You also can’t get domain information from Whois-RWS. We provide Whois-RWS documentation here.

If you’re using scripts or developing applications to get Whois data, both Whois/RDAP and Whois-RWS provide an Application Programming Interface (API) that allows you to build queries to get data directly. We provide more information about those commands for Whois-RWS and RDAP on our site.

For users wanting to use a command-line interface to get Whois data, ARIN provides a traditional Whois service that you can access through a terminal window, and we offer NicInfo, our RDAP client. We provide more information about using the CLI, including some command examples, on our site.

So to summarize: if you want to use a fast web tool that gives results from the most sources, give Whois/RDAP a try! If you’re only looking for ARIN-managed resources, or if you don’t want to change to a new search tool just yet, you can still use Whois-RWS. If you want a bare-bones CLI, we’ve got you covered with our Whois “port 43” service. And if you need to get Whois data programmatically, we suggest trying RDAP so you can search for ARIN and other RIR/registrar resources all from one place.

Need more info? Head here:

  • Using Whois
  • Whois/RDAP
  • Whois-RWS

Still have questions? You can contact us, or sign up for the Technical Discussions mailing list and ask questions of others in the community.

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