We scanned lets say 15k machines, and I might add by scan I mean PING sweep. And THAT took 4 days.
So lets say AT best 4K machines pinged per day. Lets say it takes just as long to ping a machine as it does to scan a single port on that machine. That means we’re looking at the better part of 245,756 days if we’re scanning every single port on 4k machines. 20k machines… in theory? Approximately three thousand years? I’m hoping my math is a bit off there.