Pas d'enregistrement AAAA, ça ne risque pas de répondre en v6 :
$ host twitter.com
twitter.com. has IPv4 address 104.244.42.129
twitter.com. has IPv4 address 104.244.42.1
Host twitter.com. has no AAAA record
twitter.com. mail is handled by 20 alt2.aspmx.l.google.com.
twitter.com. mail is handled by 30 ASPMX3.GOOGLEMAIL.com.
twitter.com. mail is handled by 30 ASPMX2.GOOGLEMAIL.com.
twitter.com. mail is handled by 20 alt1.aspmx.l.google.com.
twitter.com. mail is handled by 10 aspmx.l.google.com.