During the 2+ weeks for which Site Finder was operational, a number of ISPs took steps to disable the service. A study just released reveals details and analysis, including specific networks disabling Site Finder during its operational period. For example, China blocked the traffic at its backbone, and Taiwan’s Chunghwa Telecom and Korea’s DACOM also disabled the service.  US ISPs seem to have been slower to act, in general — but US ISP Adelphia disabled the service September 20-22 before re-enabling it on September 23.

As part of its discussion, the analysis further reveals:

“We find evidence that at least a handful of networks have disabled Site Finder, but that at least some of these networks are extremely large (e.g. China). From the majority of these networks, Site Finder traffic has dropped off significantly since the introduction of the service — supporting the inference that Site Finder was blocked on these networks sometime subsequent to the service’s introduction (typically during the week of September 22). In addition, at a few large networks, Site Finder never reached significant traffic — supporting the inference that the corresponding ISPs blocked the Site Finder service quickly.

Our analysis indicates that approximately 9% of Internet users at the time of the study did not receive Site Finder when they request a nonexistent .COM or .NET domain. More than half of this proportion results from China’s apparent decision, effective beginning September 24-25, to block Site Finder, while the remainder reflects other network operators jointly. We reach these estimates using Alexa data as to web usage by network — logs that tell us what proportion of web browsing (of sites generally) comes from which networks, allowing us to estimate the amount of web traffic likely to result from the networks we have identified. Of course, the accuracy of our ultimate estimate requires certain assumptions — namely that Site Finder page request counts are proportional to ordinary web browsing traffic, and that Alexa users connect to the Internet via designated networks in proportion to the networks’ overall web usage and user base.

We observe that the majority of networks blocking access to Site Finder are located outside the United States. To some extent this result may reflect greater centralized coordination of networks in certain countries, e.g. China, allowing faster or more successful response to network changes deemed undesirable. We note, however, that Site Finder is blocked by networks in countries with no special experience at Internet filtering (e.g. Greece, Korea, Russia). We also note that relatively more intense blocking of Site Finder outside the US is precisely as anticipated by two distinct sets of concerns:

1. That Site Finder pages are always presented in English (notwithstanding users’ language preferences)

2. That Site Finder pages are larger than ordinary error messages and therefore slower and more costly to transmit.

Both these concerns disproportionately affect non-US users — for whom English web pages are less likely to be useful than pages in native languages, and for whom data transfer cost and speed constraints may be particularly acute. Meanwhile, we consider equally noteworthy our finding that relatively few large US ISPs have made efforts to block Site Finder.”

Details and additional analysis, including specific networks disabling Site Finder, are located at:

Technical Responses to Unilateral Internet Authority: The Deployment of VeriSign “Site Finder” and ISP Response.

If you have additional information about networks on which Site Finder was or was not accessible, please consider submitting your experience.

Jonthan Zittrain and Ben Edelman
Berkman Center for Internet & Society
Harvard Law School