Multicast DNS (mDNS), as specified in IETF RFC 6762, provides HostName resolution without needing a DNS server. Hosts needing to resolve HostNames issue mDNS queries to the well-known IP multicast address for mDNS.

In discovering UAFX Servers, Clients may use mDNS directly or the local discovery server-multicast extension (mDNS-ME), as described in OPC 1000012.

Figure 4 illustrates the use of mDNS for HostName resolution during UAFX connection establishment.


Figure 4 – Client Server with mDNS resolution