How often are the pings? Do the pings wait for startup or timeout? A lot of filtering methods on the traffic data could ignore isolated pings as well. They don't have to be using on/off. They could be using a higher threshold. E.g. one ping every 10 minutes, just startup and handle it then shutdown. 10 page loads every 10 minutes? Startup and stay up for 10 minutes. It's weird to even call page loads pings rather than the actual traditional ping as well, but whatever.