It indeed seems to take some time to fail:
$ dig +short aaaa archive.ubuntu.com 2001:67c:1360:8001::21 2001:67c:1560:8001::11 2001:67c:1360:8001::17 2001:67c:1562::19 2001:67c:1560:8001::14
$ curl -v --connect-timeout 10 http://[2001:67c:1360:8001::21]/ * Trying 2001:67c:1360:8001::21... * Connection timed out after 10001 milliseconds * Closing connection 0 curl: (28) Connection timed out after 10001 milliseconds
It indeed seems to take some time to fail:
$ dig +short aaaa archive.ubuntu.com 1360:8001: :21 1560:8001: :11 1360:8001: :17 1560:8001: :14
2001:67c:
2001:67c:
2001:67c:
2001:67c:1562::19
2001:67c:
$ curl -v --connect-timeout 10 http://[2001:67c: 1360:8001: :21]/ 1360:8001: :21...
* Trying 2001:67c:
* Connection timed out after 10001 milliseconds
* Closing connection 0
curl: (28) Connection timed out after 10001 milliseconds