In our scenario  we want the firewall to act as NDP Proxy for the prefixes on devices behind the firewall When the firewall is NDP Proxy for a specified set of addresses/ranges/prefixes  and it sees an address from this range in an ND solicitation or advertisement  the firewall will respond as long as a device with that specific address doesn’t respond first  the address is not negated in the NDP proxy configuration  and the address is not in the ND cache