Study Reports Filtering Results in "Overblocking"

Filtering the Internet by blocking IP addresses is imprecise and overbroad, says a recent study from Harvard University. The study, conducted by Benjamin Edelman of Harvard's Berkman Center for Internet and Society, found that over 87% of active websites resided on servers with two or more domain names. Almost 70% of active websites resided on servers with 50 or more domains. The study concluded that, as a practical matter, the filtering of undesirable web content (whether "undesirable" is defined as pornographic, hate speech, or political dissent) by blocking server IP addresses causes harm by blocking unrelated and potentially innocent websites that happen to share the same IP address. Edelman's review of a sample of IP addresses hosting 1000 or more domains suggested that there was a significant diversity between active websites hosted on a single server. For instance, servers hosting sexually-explicit websites were also found to host unrelated non-sexually-explicit websites. Edelman also suggested that there were significant constitutional implications of attempting to screen out individual websites by blocking entire IP addresses. For a copy of the Study, visit: http://cyber.law.harvard.edu/people/edelman/ip-sharing/