This notification is triggered when a duplicate IPv6 address assignment is detected. This notification is generated if a client sends a Decline message. The DHCPv6 client is required to do Duplicate Address Detection (DAD) before using the address and therefore would send the Decline message if it found that the address was in use. The DHCP server marks the IP address as unavailable for leasing to clients. cnrdhcpv6DupIpv6Address indicates the IPv6 address that triggered this event, cnrdhcpv6ClientId and cnrdhcpv6ClientLookupKey indicate the client identifier option and lookup key for the client that triggered this event and cnrdhcpv6DupIpv6AddressDetectedBy object indicates whether the client or server detected this condition.