From WHOIS to RDAP: Are IP Lookup Services Getting any Better?

Registration data have several important applications, for instance, in web security and Internet economics. For this reason, they have been made publicly available since the early days of the Internet through the WHOIS lookup service. However, WHOIS provides human-readable textual data without a strict data model, thereby hindering machine interpretation. This work provides a thorough analysis of the Registration Data Access Protocol (RDAP), the successor of WHOIS, with particular focus on its suitability for modern cloud-based applications requiring machine-friendly data and short response times. Accordingly, an in-depth analysis is carried out over a dataset of more than 360k RDAP records as for both the content of the responses and the performance of the protocol in comparison with WHOIS. The analysis reveals that RDAP records are complex to parse, redundant, and subject to response times with high variance. These findings are leveraged to provide recommendations on the future evolution of RDAP to satisfy the requirements of modern applications.