Multiplicity resolves a DNS name to a single IP address and then tries to connect to it.  This is not proper behavior for a network application.  When a machine registers more than one IP Address in DNS, an application should respect all of them and try and connect to each in order.  On Windows, the DNS resolve API sorts the IP addresses in 'most likely to connect' order, but it does not guarantee that IPAddress[0] is the only one you need to try.