Root domains

Every observed server name folded to its registrable domain (eTLD+1), so subdomain sprawl collapses — the hundreds of per-widget *.w.hcaptcha.com hosts become one hcaptcha.com. hostnames is the distinct SNIs folded in; clients the distinct fingerprints reaching it. Many observations behind few clients is one operator hammering — sort by targeting to surface it. 0 domains.