Vint Cerf about IPv4's 32-bit address length (posted 2014-07-04)
A few weeks ago, I wrote With the Americas running out of IPv4, it's official: The Internet is full for Ars Technica, where I explain where all the IPv4 addresses went.
In the comments, a reader posted a link to an interview with Vint Cerf where Cerf explains how we ended up with the limited 32-bit IPv4 address space. Well worth a listen. The 32-bit thing starts 26 minutes in. Basically, IPv4 is the test version of IP, and IPv6 is the production version!
After so many of his shows degraded into "Leo jokes around with his friends" I had forgotten how good an interviewer Leo Laporte is. There's also another longer interview with Vint Cerf.