3.3.5 Processing Events and Sequencing Rules
When a client receives a NAT_RESOLVER_RESPONSE message, it SHOULD validate that wMessageIDEcho and dwSourceIDEcho correspond to values that it sent in a previous NAT_RESOLVER_QUERY message's wMessageID and dwSourceID fields. If not, the packet MUST be silently ignored. Otherwise, the client SHOULD reverse the exclusive-or (XOR) bitwise operation performed on the dwIPv4Address and wPort fields, and save the resulting address and port information for use in advertising the DirectPlay 8 Protocol: Core and Service Providers game session. The Retry Timer SHOULD then be canceled.
If the NAT_RESOLVER_RESPONSE message is not properly formed as described in section 2.2.4, the client MUST ignore the message.
If a client receives a NAT_RESOLVER_QUERY message, it MUST be silently ignored.