Apple OS X 10.11 and iOS 9 now prefer IPv6 for connections
Thanks to an improved Happy Eyeballs implementation (Erick Vyncke says 25 ms instead of the 300 ms specified in RFC 6555) that went from roughly 50/50 IPv4/IPv6 in iOS 8 and OS X 10.10 to about 99% IPv6 in iOS 9 and OS X 10.11.
This is good news, when you think that now ARIN also “ran out of IPv4 addresses”; i.e. was unable to meet a legitimate demand for IPv4 address space as from 1 July 2015. (This does not mean there are no more IPv4 addresses, it just means that for the first time ARIN could not satisfy a valid demand for address space).
▻https://www.arin.net/resources/request/waiting_list.html
#IPv6