This read-create InetAddressIPv6 stores the MAP domain's end-user IPv6 prefix, the block from which the subscriber's mapped IPv4 address and port set are algorithmically derived. An admin verifies this value matches what the ISP's DHCPv6 or provisioning system assigned to confirm the MAP mapping will compute correctly. For example, a mismatch between this configured prefix and the prefix actually delegated to the WAN interface would break the customer's IPv4 connectivity through MAP.