I remember realizing I could use that trick to getting around a bluecoat proxy back in 2004. I worked in a bank, and they had draconian web filtering. DNS looku

I remember realizing I could use that trick to getting around a bluecoat proxy back in 2004. I worked in a bank, and they had draconian web filtering. DNS lookups weren't blocked, but the eeb proxy blocked sites by domain name and the ipv4 address it resolved to. However, it didn't block the ip address if you formatted it as a single 32bit integer! Of course, that would break if there was a redirect or https, but back then many sites didn't have those.