「 The most important change from IPv4 to IPv6 was moving from 32-bit to 128-bit addresses, a decision that increased the available pool of IP addresses from around 4.3 billion to over 340 undecillion – a 39-digit number. IPv6 was therefore thought to have future-proofed the internet, because nobody could imagine humanity would ever need more than a handful of undecillion IP addresses, never mind the entire range available under IPv6 」