What is the default subnet mask for an ipv6 address ?

There are 3 address types in v6 - Unicast, anycast, and multicast. Unicast addresses identify a single network device, anycast and multicast addresses identify a group of network devices. IPv6 addresses are 128 bit, compared to the 32 bit addresses of v4 and look like this example - 2001:0db8:85a3:08d3:1319:8a2e: 0370:7348Ipv6 does not use subnetting.