3.1.3 Initialization

A DirectPlay Server/Host MUST be hosting a game session before it can respond to any EnumQuery messages.

Note that when using the IPv4 or IPv6 service provider, a DirectPlay Server/Host can specify which UDP port to use to listen for incoming messages. The DirectPlay Client/Peer MUST be aware of this port selection in order to direct the EnumQuery message to the correct port. UDP port 6073 has been registered with IANA for use by DirectPlay 8. If the DirectPlay 8 application has no compelling reason to use a different port, this is a good port to choose on an IPv4 or IPv6 network. Because this port is registered with IANA (as specified in [IANAPORT]), and is used by multiple games, it increases the likelihood that some firewalls might be preconfigured to allow traffic on this port. However, a game can use any port it deems appropriate, according to the rules and customs of the IP networks that it is using.