While working on an TCP/IP problem today, I was finally struck by the fact that we have for all intents and purposes expended the entire TCPv4 addressing space. I knew it was coming, years ago, but now while testing IP addresses, it dawned on me.
You can now pick any arbitrary set of numbers nnn.nnn.nnn.nnn and expect a response. Ping them, probe them, something will be there, or it’s being held. All gone, this is the equivalent of spitting in the middle of an ocean while swimming, you are going to hit ocean.
4,294,967,296 (232) addresses gone, 4 Billion addresses in use…..