ping to IPv6 host

Type the command as follows:

$ ping6 localhost
$ ping6 host.domain.com
$ ping6 IPv6-address
$ ping6 2001:4860:b002::68

The best way is to ping global website such as ipv6.google.com, enter:
$ ping6 ipv6.google.com

Sample output:

ping6 ipv6.google.com
PING ipv6.google.com(2001:4860:b002::68) 56 data bytes
64 bytes from 2001:4860:b002::68: icmp_seq=0 ttl=59 time=58.4 ms
64 bytes from 2001:4860:b002::68: icmp_seq=1 ttl=59 time=56.4 ms
64 bytes from 2001:4860:b002::68: icmp_seq=2 ttl=59 time=62.1 ms
64 bytes from 2001:4860:b002::68: icmp_seq=3 ttl=59 time=56.8 ms
64 bytes from 2001:4860:b002::68: icmp_seq=4 ttl=59 time=56.5 ms
64 bytes from 2001:4860:b002::68: icmp_seq=5 ttl=59 time=59.5 ms

--- ipv6.google.com ping statistics ---
6 packets transmitted, 6 received, 0% packet loss, time 5002ms
rtt min/avg/max/mdev = 56.443/58.329/62.150/2.045 ms, pipe 2

Read ping6 man page for more information:
$ man ping6