Comment by heffer

CloudFlare and friends use a multitude of factors, AS being only one of them. I am a TekSavvy customer (Canada's largest independent, i.e. not owned by one of the incumbents, ISP). Pretty clearly an eyeball network, and I get the CloudFlare captcha multiple times per day on different sites. I'm guessing it may have to do with the fact that I use custom reverse DNS entries (instead of their default schema of 127.0.0.1.dsl.teksavvy.com) for my internet facing IPv4 and IPv6 subnet.