Probably because I don't give Java free rein on my PC:
OTOH, the standard ping and traceroute commands work just fine (and test both IPv4 and IPv6 connectivity):
[code]
C:\>ping -4 www.comcast.net
Pinging a1526.dscg.akamai.net [23.62.111.147] with 32 bytes of data:
Reply from 23.62.111.147: bytes=32 time=19ms TTL=58
Reply from 23.62.111.147: bytes=32 time=18ms TTL=58
Reply from 23.62.111.147: bytes=32 time=19ms TTL=58
Reply from 23.62.111.147: bytes=32 time=19ms TTL=58
Ping statistics for 23.62.111.147:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 18ms, Maximum = 19ms, Average = 18ms
C:\>ping www.comcast.net
Pinging a1526.dscg.akamai.net [2001:559:0:501::48f6:2d1b] with 32 bytes of data:
Reply from 2001:559:0:501::48f6:2d1b: time=19ms
Reply from 2001:559:0:501::48f6:2d1b: time=19ms
Reply from 2001:559:0:501::48f6:2d1b: time=20ms
Reply from 2001:559:0:501::48f6:2d1b: time=18ms
Ping statistics for 2001:559:0:501::48f6:2d1b:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 18ms, Maximum = 20ms, Average = 19ms
C:\>tracert -4 www.comcast.net
Tracing route to a1526.dscg.akamai.net [23.62.111.185]
over a maximum of 30 hops:
1 tracert www.comcast.net
Tracing route to a1526.dscg.akamai.net [2001:559:0:501::48f6:2d41]
over a maximum of 30 hops:
1