There are two UAFX communication scenarios where HostName resolution could be used: with UA Client Server communications, such as during UAFX connection establishment, and PubSub communications to exchange the real-time data for a Connection.

Figure 2 illustrates the use of DNS (as specified in RFC 1034 and its related RFCs) in the establishment of a UAFX Connection between two UAXF Controllers.

Figure 2 – Client/server with DNS resolution

Controller A, with ConnectionManager (CM), has a DNS client and has been configured via DHCP or vendor-specific means with the IP address of the DNS server(s). The DNS server is contacted to resolve the HostName of Controller B, if not already resolved as part of UA session establishment, before issuing the EstablishConnections Method.

Figure 3 illustrates the use of DNS in conjunction with PubSub for controller-to-controller communications.

Figure 3 – PubSub with DNS resolution

In this case, via the EstablishConnections Method, each Controller has been given a PubSub configuration containing the other Controller's HostName. In order to send and receive publications, the HostNames need to be resolved to IP addresses. Each Controller has a DNS client and, if not already resolved, needs to contact the DNS server before publishing to the subscribing Controller.