Abstract: A communication system in which client and server communication systems are coupled over a data network. A request to communicate with one of the server communication systems is accepted and based on an identification of the server communication system in the request, one of a set of transport layer protocols is selected for communication between the client and server systems. The set of transport layer protocols can be determined by retrieving information from a directory service computer, such as an Internet Domain Name Server (DNS), where the address of the directory service computer is related to the identification of the server communication system. In addition, the server communication system can include an address translation table that associates a network address provided by a client communication system with local network addresses of server computers.