You are making zero sense. The point is the ids are random, so yes there are 74 quintillion possibilities. And roughly 74 quintillion 404’s. You need to check all of them. If you want to keep up with them you need to check them often. No one has the cash to check 74 quintillion anything even with a million 386s. Even the 386sx.

You won’t know if you’ll get a 404 until you make a network request. How many of those can you make per second? Hundreds? Thousands? Let’s be very generous and say millions.

That means you just need millions of years to go through the entire range.