Unlike DHCPv4, which is invoked by manual configuration, DHCPv6 is invoked by Router Advertisements (RAs). Depending on how the router is configured, the system automatically invokes DHCPv6 on the interface on which the Router Advertisement message was received and uses DHCP to get an address and other parameters, or the system requests only data other than an address (for example, DNS servers) with DHCPv6.
The in.ndpd daemon receives the Router Advertisement message. It does this automatically on all interfaces plumbed for IPv6 on the system. When in.ndpd sees an RA that specifies that DHCPv6 should run, it invokes it.
To prevent in.ndpd from starting up DHCPv6, you can change the /etc/inet/ndpd.conf file.
You can also stop DHCPv6 after it starts by using one of the following versions of ifconfig:
ifconfig <interface> inet6 dhcp drop
ifconfig <interface> inet6 dhcp release