“You’ll know that most of the Internet runs on IP version 4, the
first cut of the Internet Protocol to see widespread use. It was
standardised in 1981; for the past twenty five years or so, it’s
underpinned the beyond-massive expansion of the Internet.“You’ll also know, if you’ve heard of IPv4, that a long time ago
it was realised that it was going to hit problems at some
point…”