There are some companies that have just started to dual stack (IPv4 & IPv6) their infrastructure, like twimg (the twitter hosting images site).
Reminder that IPv6 is preferable on the Internet (by design)
query[AAAA] pbs.twimg.com from 192.168.1.4 pbs.twimg.com to xxx.xxx.xxx.xxx reply pbs.twimg.com isreply ipv6.twimg.com is 2606:1f80:a000:102::2 reply ipv6.twimg.com is 2606:1f80:a000:106::2 reply ipv6.twimg.com is 2606:1f80:a000:105::2 reply ipv6.twimg.com is 2606:1f80:a000:107::2 reply ipv6.twimg.com is 2606:1f80:a000:104::2 reply ipv6.twimg.com is 2606:1f80:a000:100::2 reply ipv6.twimg.com is 2606:1f80:a000:101::2 reply ipv6.twimg.com is 2606:1f80:a000:103::2 query[A] pbs.twimg.com from 192.168.1.4 cached pbs.twimg.com is forwarded pbs.twimg.com to xxx.xxx.xxx.xxx reply pbs.twimg.com is reply ipv6.twimg.com is 104.244.43.103 reply ipv6.twimg.com is 104.244.43.231 reply ipv6.twimg.com is 104.244.43.135 reply ipv6.twimg.com is 104.244.43.39 reply ipv6.twimg.com is 104.244.43.199 reply ipv6.twimg.com is 104.244.43.71 reply ipv6.twimg.com is 104.244.43.7 reply ipv6.twimg.com is 104.244.43.167
but twitter itself, doesnt support IPv6 !
query[AAAA] twitter.com from 192.168.1.4 forwarded twitter.com to xxx.xxx.xxx.xxx reply twitter.com is NODATA-IPv6 query[A] twitter.com from 192.168.1.4 forwarded twitter.com to xxx.xxx.xxx.xxx reply twitter.com is 199.16.156.102 reply twitter.com is 199.16.156.70 reply twitter.com is 199.16.156.38 reply twitter.com is 199.16.156.6
So below is the result on IPv4 twitter that calls IPv6 twimg: