188.8.131.52.1 Using Seed Servers
If the application or higher-layer protocol specified one or more seed server, then the PNRP node SHOULD use those seed servers. Otherwise, the PNRP node SHOULD use any seed servers it is configured with for the cloud, and if none exist, it MUST set CloudDiscoveryMode to LocalOOB.
Microsoft provides machines with the DNS names PNRPV2.IPV6.MICROSOFT.COM and PNRPV21.IPV6.MICROSOFT.COM, which act as seed servers to the Microsoft Global PNRP Cloud. The IPv6 Addresses of these machines MUST be determined via DNS lookups. A PNRP node SHOULD first perform a DNS lookup of PNRPV2.IPV6.MICROSOFT.COM and PNRPV21.IPV6.MICROSOFT.COM. The node SHOULD<3> then combine the results from the two queries, and sort the resulting address list by using the algorithm as specified in [RFC3484] section 6.
If CurrentSeedServerAddressIndex is greater than the number of addresses in the list, CurrentSeedServerAddressIndex MUST be set to zero. The node MUST select the address in the list at the index equal to CurrentSeedServerAddressIndex, increment CurrentSeedServerAddressIndex, initiate a synchronization conversation (as specified in section 184.108.40.206) to the address selected by using UDP port 3540, and finally set CloudDiscoveryMode to LocalOOB.