Always use challenge -1 to trigger a challenge response
Always use challenge -1 to trigger a challenge response

Although not technically needed for servers using the valve SDK, use a challenge of -1 (0xFFFFFFFF) instead of 0 to trigger a challenge response as that's whats documented:
https://developer.valvesoftware.com/wiki/Server_queries#Request_Format_5

This improves compatibility with 3rd party implementations of the a2s protocol.

multiplay/qstat,multiplay/qstat,multiplay/qstat,multiplay/qstat,multiplay/qstat