Consolidated Review of Exploring EDNS-Client-Subnet Adopters in Your Free Time

This paper explores how we can use the EDNS-Client-Subnet DNS extension to map out CDNs and content providers (CPs) that support it (currently only a small number, such as Edgecast and Google). This extension carries along the client's prefix with a DNS request, allowing DNS redirection based on client address rather than resolver address. Because the requests are not authenticated in any way, the authors can query a CP with an arbitrary (or all) prefixes in order to understand where the CP would map the client. Because Google is the largest adopter, many of the measurement results focus on Google.